C programming, reading from file error?

Question

My code is not putting the text file data into line on the second pass of the while loop, and any subsequent pass. I'm sure it's a silly error but I cannot find it.

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

 FILE *fr;
 char *line,*word,*vali;
 ssize_t read;
 int i=0,sum=0,len =0,flag=0;
 const char delim[2]=" ";


 int main(int argc, char* argv[])
 {

     line = (char *)malloc(sizeof(&len)); 
     word = (char *)malloc(sizeof(&len));
     vali = (char *)malloc(sizeof(&len));

     fr = fopen(argv[1], "r");
     if(fr==NULL)
     {
         exit(EXIT_FAILURE);
     }
     while ((read = getline(&line, &len, fr)) != -1)
     {
         printf("line is %s\n", line );
         fscanf(fr,"%s%*[^\n]",word);           

         printf("%s ", word);
         vali=strtok(line, delim);
         while(vali != NULL)
         {
             sum=sum+atoi(vali);
             vali = strtok(NULL, delim);
         }
         printf("%d\n", sum);
         sum=0;
         vali=" ";
         len = strlen(line);
    }
    fclose(fr);
    if (line)
        free(line);
    return 0;
 }

`malloc(sizeof(&len))`. This doesn't look correct. What is `len`? It looks like you are allocating space for a pointer only. — Filipe Gonçalves, May 11 '15 at 08:56
Show the full program along with the contents of the file. Also, indent the code properly. — Spikatrix, May 11 '15 at 08:58
Standard Warning : Please [do not cast](http://stackoverflow.com/q/605845/2173917) the return value of `malloc()` and family in `C`. — Sourav Ghosh, May 11 '15 at 08:59
What are `len`, `line`, `word`, `vali` defined as? We could assume something and fix but, thats not the way this works. Please make sure that you put the code that can be compiled. — WedaPashi, May 11 '15 at 09:07
The code compiles, at the moment len is just the length of the first line, which should be plenty of space for everything else — Barney Chambers, May 11 '15 at 09:08
see [getline](http://manpages.ubuntu.com/manpages/utopic/en/man3/getline.3.html) — BLUEPIXY, May 11 '15 at 09:10
@BarneyChambers: your code as displayed in your question does not compile, it lacks the declaration of `line`, `word`, `vali` and `len`. — Jabberwocky, May 11 '15 at 09:12
@BarneyChambers: BLUPIXY's comment contains a link with a working example. You should look at that. — Jabberwocky, May 11 '15 at 09:17
`getline(&line, &len, fr)`, In 2nd argument you need to give the size of the `line` but, you give 0. then how it store the line from the file. — Bhuvanesh, May 11 '15 at 11:40

Barry Gackle · Answer 1 · 2015-05-11T09:25:01.037

2

If len is some integral type containing the desired length of the first line, then:

    &len

Has type pointer-to-integer, and

    sizeof(&len)

Returns the size of a pointer (8 bytes on most 64 bit systems) and

    malloc(sizeof(&len))

Allocates only 8 bytes of memory (or whatever pointer size is on your system).

This is probably at least part of the issue.

edited May 11 '15 at 09:25

answered May 11 '15 at 09:19

Barry Gackle

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C programming, reading from file error?

1 Answers1