Thread: Struct size causes freezing of program?

Dear all,

I ran into the following weird problem while trying to write a simple C program using structures. The source is as follows

Code:

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

struct filerectype { 
  char myarray [9];
};

int main() 
{
  FILE *fp;  
  fp = fopen("file.txt", "rt");
  if (!fp) {
    printf("fopen error\n");
    exit(-1);
  }

  char* line;
  struct filerectype filerec;
  while( !feof(fp) ) {
    if ( fgets (line, 100, fp) != NULL)
      puts (line);
  }
  fclose(fp);

  exit(0);
} //main()

The source compiles without problems but when I try to run the .exe file, it freezes and pops the error window "blah.exe has stopped working"

Now the weird part is, that in case I play around with the fields of struct filerectype, then the .exe runs without any problems and outputs the content of file.txt. But this is all nondeterministic, i.e. when I started to write this comment, then I wanted to illustrate with an example that it works correctly with myarray size 8 and freezes with myarray size 9, but since then I played arround with the struct fields a bit again and now it freezes with myarray size 3

I am actually using Win7 and Bloodshed 4.9.9.2 if that has any relevance, but I rather suspect that it is some coding problem which I was not able to figure out so far. The goal would be actually to write a simple program using dynamic struct chains built from the data read from the file, and I have the whole concept designed on skeleton level, but this problem is now completely blocking the coding

Thank you for any help in advance

If you have text-files, you cannot read/write structs directly.
fgets/fputs cannot handle structs, you should use fread/fwrite.

char* line=(char*)malloc(100);

replace this line at line number 17. and replace rt with r

Originally Posted by BillyTKid

If you have text-files, you cannot read/write structs directly.
fgets/fputs cannot handle structs, you should use fread/fwrite.

I did not yet use the struct variable at all, that's what made the issue weird. The fgets/fputs calls were not used on the struct but on a char pointer

Originally Posted by sagar474

char* line=(char*)malloc(100);

replace this line at line number 17. and replace rt with r

Thanks man, this seems to work. I suppose the missing of this allocation might have messed up the memory handling
Using r instead of rt is not completely clear though, because file.txt is a text file

I did not yet use the struct variable at all, that's what made the issue weird. The fgets/fputs calls were not used on the struct but on a char pointer

yes i noticed that.

A 't' in fopen isn't C standard.