How read two lines numbers from input to 2 arrays, C language? Without knowing the amount of number? in C











up vote
0
down vote

favorite












For example, input is:



12 23 32 41 45
22 11 43


lines end with 'n',



I want save nums to a and b;



a = {12, 23, 32, 41, 45}
b = {22, 11, 43}


The point is I DON'T KNOW how many number of each line.



If I know line1 n numbers and line2 m numbers, I will use "for loop", and no question.



Just like,



for(int i = 0; i < n; i++) scanf("%d", a+i);
for(int i = 0; i < m; i++) scanf("%d", b+i);


But, I DO NOT know n and m, How to do, guys?










share|improve this question
























  • Can you accept a number max for array length ?
    – Ôrel
    Nov 19 at 17:03






  • 1




    If you care about line endings, then you either need to read one character at a time with fgetc, or read a line at a time with fgets.
    – user3386109
    Nov 19 at 17:06










  • Read characters until a new line is reached, if one isn't reached, resize your buffer? You'll want to use dynamic memory allocation probably.
    – jacob
    Nov 19 at 17:07






  • 2




    A good function for reading a line at a time is getline, which was standardized in POSIX.1-2008. In comparision to fgets, it can read a line of arbitrary length into a dynamically allocated buffer. If you don't have the getline function, there are various standalone implementations of it, such as the one at github.com/ivanrad/getline .
    – Ian Abbott
    Nov 19 at 17:19










  • You could use a while loop and some arbitrary input as break condition & dynamically alloc your input array(i think).
    – ats
    Nov 19 at 17:25

















up vote
0
down vote

favorite












For example, input is:



12 23 32 41 45
22 11 43


lines end with 'n',



I want save nums to a and b;



a = {12, 23, 32, 41, 45}
b = {22, 11, 43}


The point is I DON'T KNOW how many number of each line.



If I know line1 n numbers and line2 m numbers, I will use "for loop", and no question.



Just like,



for(int i = 0; i < n; i++) scanf("%d", a+i);
for(int i = 0; i < m; i++) scanf("%d", b+i);


But, I DO NOT know n and m, How to do, guys?










share|improve this question
























  • Can you accept a number max for array length ?
    – Ôrel
    Nov 19 at 17:03






  • 1




    If you care about line endings, then you either need to read one character at a time with fgetc, or read a line at a time with fgets.
    – user3386109
    Nov 19 at 17:06










  • Read characters until a new line is reached, if one isn't reached, resize your buffer? You'll want to use dynamic memory allocation probably.
    – jacob
    Nov 19 at 17:07






  • 2




    A good function for reading a line at a time is getline, which was standardized in POSIX.1-2008. In comparision to fgets, it can read a line of arbitrary length into a dynamically allocated buffer. If you don't have the getline function, there are various standalone implementations of it, such as the one at github.com/ivanrad/getline .
    – Ian Abbott
    Nov 19 at 17:19










  • You could use a while loop and some arbitrary input as break condition & dynamically alloc your input array(i think).
    – ats
    Nov 19 at 17:25















up vote
0
down vote

favorite









up vote
0
down vote

favorite











For example, input is:



12 23 32 41 45
22 11 43


lines end with 'n',



I want save nums to a and b;



a = {12, 23, 32, 41, 45}
b = {22, 11, 43}


The point is I DON'T KNOW how many number of each line.



If I know line1 n numbers and line2 m numbers, I will use "for loop", and no question.



Just like,



for(int i = 0; i < n; i++) scanf("%d", a+i);
for(int i = 0; i < m; i++) scanf("%d", b+i);


But, I DO NOT know n and m, How to do, guys?










share|improve this question















For example, input is:



12 23 32 41 45
22 11 43


lines end with 'n',



I want save nums to a and b;



a = {12, 23, 32, 41, 45}
b = {22, 11, 43}


The point is I DON'T KNOW how many number of each line.



If I know line1 n numbers and line2 m numbers, I will use "for loop", and no question.



Just like,



for(int i = 0; i < n; i++) scanf("%d", a+i);
for(int i = 0; i < m; i++) scanf("%d", b+i);


But, I DO NOT know n and m, How to do, guys?







c scanf






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 19 at 19:54









ReAl

560216




560216










asked Nov 19 at 16:58









user7331489

1




1












  • Can you accept a number max for array length ?
    – Ôrel
    Nov 19 at 17:03






  • 1




    If you care about line endings, then you either need to read one character at a time with fgetc, or read a line at a time with fgets.
    – user3386109
    Nov 19 at 17:06










  • Read characters until a new line is reached, if one isn't reached, resize your buffer? You'll want to use dynamic memory allocation probably.
    – jacob
    Nov 19 at 17:07






  • 2




    A good function for reading a line at a time is getline, which was standardized in POSIX.1-2008. In comparision to fgets, it can read a line of arbitrary length into a dynamically allocated buffer. If you don't have the getline function, there are various standalone implementations of it, such as the one at github.com/ivanrad/getline .
    – Ian Abbott
    Nov 19 at 17:19










  • You could use a while loop and some arbitrary input as break condition & dynamically alloc your input array(i think).
    – ats
    Nov 19 at 17:25




















  • Can you accept a number max for array length ?
    – Ôrel
    Nov 19 at 17:03






  • 1




    If you care about line endings, then you either need to read one character at a time with fgetc, or read a line at a time with fgets.
    – user3386109
    Nov 19 at 17:06










  • Read characters until a new line is reached, if one isn't reached, resize your buffer? You'll want to use dynamic memory allocation probably.
    – jacob
    Nov 19 at 17:07






  • 2




    A good function for reading a line at a time is getline, which was standardized in POSIX.1-2008. In comparision to fgets, it can read a line of arbitrary length into a dynamically allocated buffer. If you don't have the getline function, there are various standalone implementations of it, such as the one at github.com/ivanrad/getline .
    – Ian Abbott
    Nov 19 at 17:19










  • You could use a while loop and some arbitrary input as break condition & dynamically alloc your input array(i think).
    – ats
    Nov 19 at 17:25


















Can you accept a number max for array length ?
– Ôrel
Nov 19 at 17:03




Can you accept a number max for array length ?
– Ôrel
Nov 19 at 17:03




1




1




If you care about line endings, then you either need to read one character at a time with fgetc, or read a line at a time with fgets.
– user3386109
Nov 19 at 17:06




If you care about line endings, then you either need to read one character at a time with fgetc, or read a line at a time with fgets.
– user3386109
Nov 19 at 17:06












Read characters until a new line is reached, if one isn't reached, resize your buffer? You'll want to use dynamic memory allocation probably.
– jacob
Nov 19 at 17:07




Read characters until a new line is reached, if one isn't reached, resize your buffer? You'll want to use dynamic memory allocation probably.
– jacob
Nov 19 at 17:07




2




2




A good function for reading a line at a time is getline, which was standardized in POSIX.1-2008. In comparision to fgets, it can read a line of arbitrary length into a dynamically allocated buffer. If you don't have the getline function, there are various standalone implementations of it, such as the one at github.com/ivanrad/getline .
– Ian Abbott
Nov 19 at 17:19




A good function for reading a line at a time is getline, which was standardized in POSIX.1-2008. In comparision to fgets, it can read a line of arbitrary length into a dynamically allocated buffer. If you don't have the getline function, there are various standalone implementations of it, such as the one at github.com/ivanrad/getline .
– Ian Abbott
Nov 19 at 17:19












You could use a while loop and some arbitrary input as break condition & dynamically alloc your input array(i think).
– ats
Nov 19 at 17:25






You could use a while loop and some arbitrary input as break condition & dynamically alloc your input array(i think).
– ats
Nov 19 at 17:25














3 Answers
3






active

oldest

votes

















up vote
1
down vote













If you would like to continue using a scanf approach, I would recommend the negated scanset %[^] format specifier.



scanf("%[^n]", pointerToCharArray)



This should read in any number of characters up to but not including the character specified (which, in our case, is a newline). If you'd like to discard the newline, read it in as follows:



scanf("%[^n]n", pointerToCharArray)



A link to the reference page can be found below. The negated scanset specifier is included in the list:



http://www.cplusplus.com/reference/cstdio/scanf/



From this point, it is a simple matter to use strtok() to tokenize the output of the scanf into number arrays. If you are not familiar with strtok, another reference link is provided below:



http://www.cplusplus.com/reference/cstring/strtok/



I hope this helps!






share|improve this answer





















  • scanf("%[^n]n", pointerToCharArray) not only consumes a following newline, it waits for additional input consuming all other white-spaces. scanf() then does not return until following non-whitespace detected or EOF.
    – chux
    Nov 19 at 18:57












  • As OP is concerned about "I DON'T KNOW how many number ", using "%[^n]" without a width limit is fragile code.
    – chux
    Nov 19 at 18:58










  • Thank you very much!
    – user7331489
    Nov 22 at 8:43


















up vote
0
down vote













Let us use the non standard getline, a common library extension. @Abbott to read the entire line into allocated memory.



If an array is needed and its size determined at run-time, use a variable length array available in C99 and optionally in C11.



Make a function to count and maybe save the numbers. Use strto...() functions for robust parsing.



size_t count_longs(char *line, long *dest) {
size_t count = 0;
char *s = line;
for (;;) {
char *endptr;
long num = strtol(s, &endptr, 10);
if (s == endptr) {
break; /// no conversion
}
s = endptr;
if (dest) {
dest[count] = num;
}
count++;
}
return count;
}


Sample code snippet



  char *line = NULL;
size_t len = 0;
ssize_t nread = getline(&line, &len, stdin); // read the whole line
if (nread != -1) {
// successful read

long a[count_longs(line, NULL)]; // determine array size and use a
count_longs(line, a); // 2nd pass: assign array elements.

nread = getline(&line, &len, stdin);
if (nread != -1) {
// successful read

long b[count_longs(line, NULL)];
count_longs(line, b);

// Do something with a and b
}
}
free(line);
len = 0;





share|improve this answer






























    up vote
    0
    down vote













    A solution that could potentially fit what OP asked for would be the code below.
    The solution reads an unspecified number of integer values & stores them in arr. to break the loop/end input simply input a non-integer value. This could be further specified to search for a specific input etc.



    int c = 0;
    int *arr = NULL;
    int *extArr = NULL;
    int i = 0;
    for (i = 0; scanf("%d", &c) == 1; i++)
    {
    extArr = (int*)realloc(arr, (i+1) * sizeof(int));
    arr = extArr;
    arr[i] = c;

    }
    free(arr);


    I would, however personally go with a mix between the solution i provided & armitus answer(if i cant use getline or similar) since reallocating memory for every single int value seems redundant to me.



    Edit Since there has been some question about the code i provided and how to best use it in order to fulfill the OP's question. The codesnippet was supposed to showcase how one might create his own scanf-style function for unspecified number of integer inputs reading one full array at a time(in that case the free() has to be omitted till one is done with the array(obviously).






    share|improve this answer























    • I do see a functional problem. scanf("%d", &c) will read through an end-of-line like any other white-space. I'd expect OP's two lines of integers to end up in one arr here.
      – chux
      Nov 19 at 19:02










    • The idea was to use my codesnippet as a standalone function & then just call it n times for the number of array's required. i admittedly omitted those details from my answer.
      – ats
      Nov 19 at 19:06










    • Trouble is we do not know n prior to reading the line.
      – chux
      Nov 19 at 19:08










    • Maybe i should've phrased that better. I did not mean n as in array length, but n as in number of array's read. Since the codesnippet can easily be packed inside a function and used as a sort of scanf-overload for array's
      – ats
      Nov 19 at 19:10











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    3 Answers
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    up vote
    1
    down vote













    If you would like to continue using a scanf approach, I would recommend the negated scanset %[^] format specifier.



    scanf("%[^n]", pointerToCharArray)



    This should read in any number of characters up to but not including the character specified (which, in our case, is a newline). If you'd like to discard the newline, read it in as follows:



    scanf("%[^n]n", pointerToCharArray)



    A link to the reference page can be found below. The negated scanset specifier is included in the list:



    http://www.cplusplus.com/reference/cstdio/scanf/



    From this point, it is a simple matter to use strtok() to tokenize the output of the scanf into number arrays. If you are not familiar with strtok, another reference link is provided below:



    http://www.cplusplus.com/reference/cstring/strtok/



    I hope this helps!






    share|improve this answer





















    • scanf("%[^n]n", pointerToCharArray) not only consumes a following newline, it waits for additional input consuming all other white-spaces. scanf() then does not return until following non-whitespace detected or EOF.
      – chux
      Nov 19 at 18:57












    • As OP is concerned about "I DON'T KNOW how many number ", using "%[^n]" without a width limit is fragile code.
      – chux
      Nov 19 at 18:58










    • Thank you very much!
      – user7331489
      Nov 22 at 8:43















    up vote
    1
    down vote













    If you would like to continue using a scanf approach, I would recommend the negated scanset %[^] format specifier.



    scanf("%[^n]", pointerToCharArray)



    This should read in any number of characters up to but not including the character specified (which, in our case, is a newline). If you'd like to discard the newline, read it in as follows:



    scanf("%[^n]n", pointerToCharArray)



    A link to the reference page can be found below. The negated scanset specifier is included in the list:



    http://www.cplusplus.com/reference/cstdio/scanf/



    From this point, it is a simple matter to use strtok() to tokenize the output of the scanf into number arrays. If you are not familiar with strtok, another reference link is provided below:



    http://www.cplusplus.com/reference/cstring/strtok/



    I hope this helps!






    share|improve this answer





















    • scanf("%[^n]n", pointerToCharArray) not only consumes a following newline, it waits for additional input consuming all other white-spaces. scanf() then does not return until following non-whitespace detected or EOF.
      – chux
      Nov 19 at 18:57












    • As OP is concerned about "I DON'T KNOW how many number ", using "%[^n]" without a width limit is fragile code.
      – chux
      Nov 19 at 18:58










    • Thank you very much!
      – user7331489
      Nov 22 at 8:43













    up vote
    1
    down vote










    up vote
    1
    down vote









    If you would like to continue using a scanf approach, I would recommend the negated scanset %[^] format specifier.



    scanf("%[^n]", pointerToCharArray)



    This should read in any number of characters up to but not including the character specified (which, in our case, is a newline). If you'd like to discard the newline, read it in as follows:



    scanf("%[^n]n", pointerToCharArray)



    A link to the reference page can be found below. The negated scanset specifier is included in the list:



    http://www.cplusplus.com/reference/cstdio/scanf/



    From this point, it is a simple matter to use strtok() to tokenize the output of the scanf into number arrays. If you are not familiar with strtok, another reference link is provided below:



    http://www.cplusplus.com/reference/cstring/strtok/



    I hope this helps!






    share|improve this answer












    If you would like to continue using a scanf approach, I would recommend the negated scanset %[^] format specifier.



    scanf("%[^n]", pointerToCharArray)



    This should read in any number of characters up to but not including the character specified (which, in our case, is a newline). If you'd like to discard the newline, read it in as follows:



    scanf("%[^n]n", pointerToCharArray)



    A link to the reference page can be found below. The negated scanset specifier is included in the list:



    http://www.cplusplus.com/reference/cstdio/scanf/



    From this point, it is a simple matter to use strtok() to tokenize the output of the scanf into number arrays. If you are not familiar with strtok, another reference link is provided below:



    http://www.cplusplus.com/reference/cstring/strtok/



    I hope this helps!







    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered Nov 19 at 17:51









    armitus

    695




    695












    • scanf("%[^n]n", pointerToCharArray) not only consumes a following newline, it waits for additional input consuming all other white-spaces. scanf() then does not return until following non-whitespace detected or EOF.
      – chux
      Nov 19 at 18:57












    • As OP is concerned about "I DON'T KNOW how many number ", using "%[^n]" without a width limit is fragile code.
      – chux
      Nov 19 at 18:58










    • Thank you very much!
      – user7331489
      Nov 22 at 8:43


















    • scanf("%[^n]n", pointerToCharArray) not only consumes a following newline, it waits for additional input consuming all other white-spaces. scanf() then does not return until following non-whitespace detected or EOF.
      – chux
      Nov 19 at 18:57












    • As OP is concerned about "I DON'T KNOW how many number ", using "%[^n]" without a width limit is fragile code.
      – chux
      Nov 19 at 18:58










    • Thank you very much!
      – user7331489
      Nov 22 at 8:43
















    scanf("%[^n]n", pointerToCharArray) not only consumes a following newline, it waits for additional input consuming all other white-spaces. scanf() then does not return until following non-whitespace detected or EOF.
    – chux
    Nov 19 at 18:57






    scanf("%[^n]n", pointerToCharArray) not only consumes a following newline, it waits for additional input consuming all other white-spaces. scanf() then does not return until following non-whitespace detected or EOF.
    – chux
    Nov 19 at 18:57














    As OP is concerned about "I DON'T KNOW how many number ", using "%[^n]" without a width limit is fragile code.
    – chux
    Nov 19 at 18:58




    As OP is concerned about "I DON'T KNOW how many number ", using "%[^n]" without a width limit is fragile code.
    – chux
    Nov 19 at 18:58












    Thank you very much!
    – user7331489
    Nov 22 at 8:43




    Thank you very much!
    – user7331489
    Nov 22 at 8:43












    up vote
    0
    down vote













    Let us use the non standard getline, a common library extension. @Abbott to read the entire line into allocated memory.



    If an array is needed and its size determined at run-time, use a variable length array available in C99 and optionally in C11.



    Make a function to count and maybe save the numbers. Use strto...() functions for robust parsing.



    size_t count_longs(char *line, long *dest) {
    size_t count = 0;
    char *s = line;
    for (;;) {
    char *endptr;
    long num = strtol(s, &endptr, 10);
    if (s == endptr) {
    break; /// no conversion
    }
    s = endptr;
    if (dest) {
    dest[count] = num;
    }
    count++;
    }
    return count;
    }


    Sample code snippet



      char *line = NULL;
    size_t len = 0;
    ssize_t nread = getline(&line, &len, stdin); // read the whole line
    if (nread != -1) {
    // successful read

    long a[count_longs(line, NULL)]; // determine array size and use a
    count_longs(line, a); // 2nd pass: assign array elements.

    nread = getline(&line, &len, stdin);
    if (nread != -1) {
    // successful read

    long b[count_longs(line, NULL)];
    count_longs(line, b);

    // Do something with a and b
    }
    }
    free(line);
    len = 0;





    share|improve this answer



























      up vote
      0
      down vote













      Let us use the non standard getline, a common library extension. @Abbott to read the entire line into allocated memory.



      If an array is needed and its size determined at run-time, use a variable length array available in C99 and optionally in C11.



      Make a function to count and maybe save the numbers. Use strto...() functions for robust parsing.



      size_t count_longs(char *line, long *dest) {
      size_t count = 0;
      char *s = line;
      for (;;) {
      char *endptr;
      long num = strtol(s, &endptr, 10);
      if (s == endptr) {
      break; /// no conversion
      }
      s = endptr;
      if (dest) {
      dest[count] = num;
      }
      count++;
      }
      return count;
      }


      Sample code snippet



        char *line = NULL;
      size_t len = 0;
      ssize_t nread = getline(&line, &len, stdin); // read the whole line
      if (nread != -1) {
      // successful read

      long a[count_longs(line, NULL)]; // determine array size and use a
      count_longs(line, a); // 2nd pass: assign array elements.

      nread = getline(&line, &len, stdin);
      if (nread != -1) {
      // successful read

      long b[count_longs(line, NULL)];
      count_longs(line, b);

      // Do something with a and b
      }
      }
      free(line);
      len = 0;





      share|improve this answer

























        up vote
        0
        down vote










        up vote
        0
        down vote









        Let us use the non standard getline, a common library extension. @Abbott to read the entire line into allocated memory.



        If an array is needed and its size determined at run-time, use a variable length array available in C99 and optionally in C11.



        Make a function to count and maybe save the numbers. Use strto...() functions for robust parsing.



        size_t count_longs(char *line, long *dest) {
        size_t count = 0;
        char *s = line;
        for (;;) {
        char *endptr;
        long num = strtol(s, &endptr, 10);
        if (s == endptr) {
        break; /// no conversion
        }
        s = endptr;
        if (dest) {
        dest[count] = num;
        }
        count++;
        }
        return count;
        }


        Sample code snippet



          char *line = NULL;
        size_t len = 0;
        ssize_t nread = getline(&line, &len, stdin); // read the whole line
        if (nread != -1) {
        // successful read

        long a[count_longs(line, NULL)]; // determine array size and use a
        count_longs(line, a); // 2nd pass: assign array elements.

        nread = getline(&line, &len, stdin);
        if (nread != -1) {
        // successful read

        long b[count_longs(line, NULL)];
        count_longs(line, b);

        // Do something with a and b
        }
        }
        free(line);
        len = 0;





        share|improve this answer














        Let us use the non standard getline, a common library extension. @Abbott to read the entire line into allocated memory.



        If an array is needed and its size determined at run-time, use a variable length array available in C99 and optionally in C11.



        Make a function to count and maybe save the numbers. Use strto...() functions for robust parsing.



        size_t count_longs(char *line, long *dest) {
        size_t count = 0;
        char *s = line;
        for (;;) {
        char *endptr;
        long num = strtol(s, &endptr, 10);
        if (s == endptr) {
        break; /// no conversion
        }
        s = endptr;
        if (dest) {
        dest[count] = num;
        }
        count++;
        }
        return count;
        }


        Sample code snippet



          char *line = NULL;
        size_t len = 0;
        ssize_t nread = getline(&line, &len, stdin); // read the whole line
        if (nread != -1) {
        // successful read

        long a[count_longs(line, NULL)]; // determine array size and use a
        count_longs(line, a); // 2nd pass: assign array elements.

        nread = getline(&line, &len, stdin);
        if (nread != -1) {
        // successful read

        long b[count_longs(line, NULL)];
        count_longs(line, b);

        // Do something with a and b
        }
        }
        free(line);
        len = 0;






        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Nov 19 at 18:19

























        answered Nov 19 at 18:05









        chux

        78.8k869145




        78.8k869145






















            up vote
            0
            down vote













            A solution that could potentially fit what OP asked for would be the code below.
            The solution reads an unspecified number of integer values & stores them in arr. to break the loop/end input simply input a non-integer value. This could be further specified to search for a specific input etc.



            int c = 0;
            int *arr = NULL;
            int *extArr = NULL;
            int i = 0;
            for (i = 0; scanf("%d", &c) == 1; i++)
            {
            extArr = (int*)realloc(arr, (i+1) * sizeof(int));
            arr = extArr;
            arr[i] = c;

            }
            free(arr);


            I would, however personally go with a mix between the solution i provided & armitus answer(if i cant use getline or similar) since reallocating memory for every single int value seems redundant to me.



            Edit Since there has been some question about the code i provided and how to best use it in order to fulfill the OP's question. The codesnippet was supposed to showcase how one might create his own scanf-style function for unspecified number of integer inputs reading one full array at a time(in that case the free() has to be omitted till one is done with the array(obviously).






            share|improve this answer























            • I do see a functional problem. scanf("%d", &c) will read through an end-of-line like any other white-space. I'd expect OP's two lines of integers to end up in one arr here.
              – chux
              Nov 19 at 19:02










            • The idea was to use my codesnippet as a standalone function & then just call it n times for the number of array's required. i admittedly omitted those details from my answer.
              – ats
              Nov 19 at 19:06










            • Trouble is we do not know n prior to reading the line.
              – chux
              Nov 19 at 19:08










            • Maybe i should've phrased that better. I did not mean n as in array length, but n as in number of array's read. Since the codesnippet can easily be packed inside a function and used as a sort of scanf-overload for array's
              – ats
              Nov 19 at 19:10















            up vote
            0
            down vote













            A solution that could potentially fit what OP asked for would be the code below.
            The solution reads an unspecified number of integer values & stores them in arr. to break the loop/end input simply input a non-integer value. This could be further specified to search for a specific input etc.



            int c = 0;
            int *arr = NULL;
            int *extArr = NULL;
            int i = 0;
            for (i = 0; scanf("%d", &c) == 1; i++)
            {
            extArr = (int*)realloc(arr, (i+1) * sizeof(int));
            arr = extArr;
            arr[i] = c;

            }
            free(arr);


            I would, however personally go with a mix between the solution i provided & armitus answer(if i cant use getline or similar) since reallocating memory for every single int value seems redundant to me.



            Edit Since there has been some question about the code i provided and how to best use it in order to fulfill the OP's question. The codesnippet was supposed to showcase how one might create his own scanf-style function for unspecified number of integer inputs reading one full array at a time(in that case the free() has to be omitted till one is done with the array(obviously).






            share|improve this answer























            • I do see a functional problem. scanf("%d", &c) will read through an end-of-line like any other white-space. I'd expect OP's two lines of integers to end up in one arr here.
              – chux
              Nov 19 at 19:02










            • The idea was to use my codesnippet as a standalone function & then just call it n times for the number of array's required. i admittedly omitted those details from my answer.
              – ats
              Nov 19 at 19:06










            • Trouble is we do not know n prior to reading the line.
              – chux
              Nov 19 at 19:08










            • Maybe i should've phrased that better. I did not mean n as in array length, but n as in number of array's read. Since the codesnippet can easily be packed inside a function and used as a sort of scanf-overload for array's
              – ats
              Nov 19 at 19:10













            up vote
            0
            down vote










            up vote
            0
            down vote









            A solution that could potentially fit what OP asked for would be the code below.
            The solution reads an unspecified number of integer values & stores them in arr. to break the loop/end input simply input a non-integer value. This could be further specified to search for a specific input etc.



            int c = 0;
            int *arr = NULL;
            int *extArr = NULL;
            int i = 0;
            for (i = 0; scanf("%d", &c) == 1; i++)
            {
            extArr = (int*)realloc(arr, (i+1) * sizeof(int));
            arr = extArr;
            arr[i] = c;

            }
            free(arr);


            I would, however personally go with a mix between the solution i provided & armitus answer(if i cant use getline or similar) since reallocating memory for every single int value seems redundant to me.



            Edit Since there has been some question about the code i provided and how to best use it in order to fulfill the OP's question. The codesnippet was supposed to showcase how one might create his own scanf-style function for unspecified number of integer inputs reading one full array at a time(in that case the free() has to be omitted till one is done with the array(obviously).






            share|improve this answer














            A solution that could potentially fit what OP asked for would be the code below.
            The solution reads an unspecified number of integer values & stores them in arr. to break the loop/end input simply input a non-integer value. This could be further specified to search for a specific input etc.



            int c = 0;
            int *arr = NULL;
            int *extArr = NULL;
            int i = 0;
            for (i = 0; scanf("%d", &c) == 1; i++)
            {
            extArr = (int*)realloc(arr, (i+1) * sizeof(int));
            arr = extArr;
            arr[i] = c;

            }
            free(arr);


            I would, however personally go with a mix between the solution i provided & armitus answer(if i cant use getline or similar) since reallocating memory for every single int value seems redundant to me.



            Edit Since there has been some question about the code i provided and how to best use it in order to fulfill the OP's question. The codesnippet was supposed to showcase how one might create his own scanf-style function for unspecified number of integer inputs reading one full array at a time(in that case the free() has to be omitted till one is done with the array(obviously).







            share|improve this answer














            share|improve this answer



            share|improve this answer








            edited Nov 19 at 19:08

























            answered Nov 19 at 18:37









            ats

            544




            544












            • I do see a functional problem. scanf("%d", &c) will read through an end-of-line like any other white-space. I'd expect OP's two lines of integers to end up in one arr here.
              – chux
              Nov 19 at 19:02










            • The idea was to use my codesnippet as a standalone function & then just call it n times for the number of array's required. i admittedly omitted those details from my answer.
              – ats
              Nov 19 at 19:06










            • Trouble is we do not know n prior to reading the line.
              – chux
              Nov 19 at 19:08










            • Maybe i should've phrased that better. I did not mean n as in array length, but n as in number of array's read. Since the codesnippet can easily be packed inside a function and used as a sort of scanf-overload for array's
              – ats
              Nov 19 at 19:10


















            • I do see a functional problem. scanf("%d", &c) will read through an end-of-line like any other white-space. I'd expect OP's two lines of integers to end up in one arr here.
              – chux
              Nov 19 at 19:02










            • The idea was to use my codesnippet as a standalone function & then just call it n times for the number of array's required. i admittedly omitted those details from my answer.
              – ats
              Nov 19 at 19:06










            • Trouble is we do not know n prior to reading the line.
              – chux
              Nov 19 at 19:08










            • Maybe i should've phrased that better. I did not mean n as in array length, but n as in number of array's read. Since the codesnippet can easily be packed inside a function and used as a sort of scanf-overload for array's
              – ats
              Nov 19 at 19:10
















            I do see a functional problem. scanf("%d", &c) will read through an end-of-line like any other white-space. I'd expect OP's two lines of integers to end up in one arr here.
            – chux
            Nov 19 at 19:02




            I do see a functional problem. scanf("%d", &c) will read through an end-of-line like any other white-space. I'd expect OP's two lines of integers to end up in one arr here.
            – chux
            Nov 19 at 19:02












            The idea was to use my codesnippet as a standalone function & then just call it n times for the number of array's required. i admittedly omitted those details from my answer.
            – ats
            Nov 19 at 19:06




            The idea was to use my codesnippet as a standalone function & then just call it n times for the number of array's required. i admittedly omitted those details from my answer.
            – ats
            Nov 19 at 19:06












            Trouble is we do not know n prior to reading the line.
            – chux
            Nov 19 at 19:08




            Trouble is we do not know n prior to reading the line.
            – chux
            Nov 19 at 19:08












            Maybe i should've phrased that better. I did not mean n as in array length, but n as in number of array's read. Since the codesnippet can easily be packed inside a function and used as a sort of scanf-overload for array's
            – ats
            Nov 19 at 19:10




            Maybe i should've phrased that better. I did not mean n as in array length, but n as in number of array's read. Since the codesnippet can easily be packed inside a function and used as a sort of scanf-overload for array's
            – ats
            Nov 19 at 19:10


















             

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