list_it.c

c21Examples.rar

/* list_it.c__This program displays a listing with line numbers! */
#include <stdio.h>
#include <stdlib.h>

void display_usage(void);
int line;

int main( int argc, char *argv[] )
{
   char buffer[256];
   FILE *fp;

   if( argc < 2 )
   {
      display_usage();
      return 1;
   }

   if (( fp = fopen( argv[1], "r" )) == NULL )
   {
        fprintf( stderr, "Error opening file, %s!", argv[1] );
        return(1);
   }

   line = 1;

   while( fgets( buffer, 256, fp ) != NULL )
      fprintf( stdout, "%4d:\t%s", line++, buffer );

   fclose(fp);
   return 0;
}

void display_usage(void)
{
      fprintf(stderr, "\nProper Usage is: " );
      fprintf(stderr, "\n\nlist_it filename.ext\n" );
}


/* Function returns the product of the two values provided */
int product(int x, int y)
{
    return (x * y);
}