Thread: Cannot Execute/Run Program

Hi everyone,

I am new to the board and not really a programmer yet but I found this book SAMS Teach Yourself C in 21 Days by Bradley Jones and Peter Aitken, so I decided to just get my head around it. I would like to have some knowledge on C somehow as I may need it in my profession in the future.

The problem is with the first "Type and Run," where the code looks like this:

Code:

/* print_it.c--This program prints a listing with line numbers! */ 
#include <stdlib.h> 
#include <stdio.h> 
 
void do_heading(char *filename); 
 
int line = 0, page = 0; 
 
int main( int argv, char *argc[] ) 
{ 
  char buffer[256]; 
  FILE *fp; 
 
  if( argv < 2 ) 
  { 
     fprintf(stderr, "\nProper Usage is: " ); 
     fprintf(stderr, "\n\nprint_it filename.ext\n" ); 
     return(1); 
  } 
 
  if (( fp = fopen( argc[1], "r" )) == NULL ) 
  { 
       fprintf( stderr, "Error opening file, %s!", argc[1]); 
       return(1); 
  } 
 
  page = 0; 
  line = 1; 
  do_heading( argc[1]); 
 
  while( fgets( buffer, 256, fp ) != NULL ) 
  { 
     if( line % 55 == 0 ) 
        do_heading( argc[1] ); 
 
     fprintf( stdprn, "%4d:\t%s", line++, buffer ); 
  } 
 
  fprintf( stdprn, "\f" ); 
  fclose(fp); 
  return 0; 
} 
 
void do_heading( char *filename ) 
{ 
   page++; 
 
   if ( page > 1) 
      fprintf( stdprn, "\f" ); 
 
   fprintf( stdprn, "Page: %d, %s\n\n", page, filename ); 
}

I am using the gcc compiler in Ubuntu 12.04 LTS and I get the following error:

Code:

print_it.c: In function ‘main’:
print_it.c:36:15: error: ‘stdprn’ undeclared (first use in this function)
print_it.c:36:15: note: each undeclared identifier is reported only once for each function it appears in
print_it.c: In function ‘do_heading’:
print_it.c:49:16: error: ‘stdprn’ undeclared (first use in this function)

I was told that "stdprn" can be recognised by a DOS based compiler and the book says I can try using "stdout" instead. It looks like this now:

Code:

/* print_it.c--This program prints a listing with line numbers! */ 
#include <stdlib.h> 
#include <stdio.h> 
 
void do_heading(char *filename); 
 
int line = 0, page = 0; 
 
int main( int argv, char *argc[] ) 
{ 
  char buffer[256]; 
  FILE *fp; 
 
  if( argv < 2 ) 
  { 
     fprintf(stderr, "\nProper Usage is: " ); 
     fprintf(stderr, "\n\nprint_it filename.ext\n" ); 
     return(1); 
  } 
 
  if (( fp = fopen( argc[1], "r" )) == NULL ) 
  { 
       fprintf( stderr, "Error opening file, %s!", argc[1]); 
       return(1); 
  } 
 
  page = 0; 
  line = 1; 
  do_heading( argc[1]); 
 
  while( fgets( buffer, 256, fp ) != NULL ) 
  { 
     if( line % 55 == 0 ) 
        do_heading( argc[1] ); 
 
     fprintf( stdout, "%4d:\t%s", line++, buffer ); 
  } 
 
  fprintf( stdout, "\f" ); 
  fclose(fp); 
  return 0; 
} 
 
void do_heading( char *filename ) 
{ 
   page++; 
 
   if ( page > 1) 
      fprintf( stdout, "\f" ); 
 
   fprintf( stdout, "Page: %d, %s\n\n", page, filename ); 
}

It compiled OK with the gcc compiler but I only get this when I run the program:

Code:

Proper Usage is: 

print_it filename.ext

I am not sure whether I should continue looking into this but even when I tried compiling and running it on Windows, the .exe file won't even launch. The other ones do but this first one doesn't.

Questions:

1. What should be done to make this program run?
2. Even though the book says "don't care" if the reader does not understand the items (It's Day 1/Lesson 1), I would still like it to run as I don't want to experience compiling and running problems in the future. Should I even bother doing this section of the book or is it obsolete and should be skipped?

Thanks.

Hmmm. I haven't read that part yet in the book as I am still in Chapter 1. I just copied and pasted the code from the examples as the the book would like the readers to try compiling and running first.

If it's copied directly and does not run as it is, there should be something wrong with it, then.

I may have to read through all the chapters and get back to this first "Type & Run." Or if anyone can help me just get this program to run, it would be very much appreciated. Thanks.

Your print_it program is telling you that it expects the name of a file as an argument (standard Usage message). Open a terminal, go to the directory where print_it is and enter ./print_it print_it.c - assuming your source file is named print_it.c

Or in Windows, go to folder, Shift-right-click the containing folder and select "Open command window here". Then enter print_it print_it.c

I got it working now. Thanks, guys.