I just started learning C with a book called "Sams | Teach Yourself C in 21 Days, 6th edition" and I've already run into a problem I can't solve. The book gives a program that is supposed to display any code from any saved source file - including its own. As the book states on page 37, "The list_it.c program in Listing 2.2 displays C program listings that you have saved. These listings are displayed on the screen with line numbers added."
The problem is that I don't know how to use it to make it work and the book doesn't give any specific instructions for using it. What am I supposed to do with it? I'm using Dev C++ and when I run it all I get is this:
Proper Usage is:
list_it filename.extI've tried renaming and recompliling this program with two different filenames - list_it multiply.c and list_it list_it.c and it just gave me scrambled junk. I've also tried opening multiply.c and using the same approach and I got the same result.
Here's the code:
/* 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" );
}
