help on reading file

[unhwan]

I have the following but doesn't work.... why?

/*
#include<stdio.h>
void main(void)
{
	FILE *infile;
	char* line;

	if((infile = fopen("info.txt", "r"))==NULL )
	{
		fprintf(stderr, "Error: Cannot open input file. ");
		exit(1);
	}

	while(fscanf(infile, "%s", line) != EOF)
		printf("%s\n", line); 
}
*/

[quzah]

It doesn't work because you haven't allocated any space for your pointers. fscanf does not allocate memory.

Quzah.

[Hammer]

void main.... don't do it!

[Prelude]

#include<stdio.h>
/* If you are going to use exit(), include
** stdlib.h. You might as well include it
** anyway so you can use the return status
** macros
*/
#include<stdlib.h>
/* void main is totally wrong, sorry */
int main(void)
{
  FILE *infile;
  /* Allocate memory or use an array, segfaults
  ** are no fun.
  */
  char line[BUFSIZ];

  if((infile = fopen("info.txt", "r"))==NULL )
  {
    /* perror is much more suited to error reporting
    ** after standard function calls, you get better
    ** information. And since you're exiting anyway,
    ** why not just return and use a more informative
    ** condition so that readers know the program is
    ** terminating due to error.
    */
    perror("Cannot open input file");
    return EXIT_FAILURE;
  }

  /* fgets is much better for line input, either from
  ** a file or from stdin.
  */
  while(fgets(line, sizeof line, infile) != NULL)
    printf("%s\n", line);

  /* Always close your files */
  fclose(infile);

  /* main returns an int, keep it portable by using
  ** either 0, EXIT_SUCCESS, or EXIT_FAILURE
  */
  return EXIT_SUCCESS;
}

-Prelude

[unhwan]

thank you prelude.