C command line args in linux

YankeeFan · 06-10-2006, 08:19 PM

I'm obviously new to linux, but having fun.
I actually have a couple of questions.

1) am I missing a search function on this site? I'd like to search for an answer before spamming everyone with a repeated question.

2) Not sure this goes here, but seems like the best place for me.

I'm re-aquainting myself to c and c++. I'm starting with the basics and going forward. I'm having a bug sending command line arguments to my program. I'm confident the code is okay, it is how to call the program from the command line I'm not sure of. The book I'm using shows it as I do it below.

The name of my program is argsc after compiling okay. I call it like so:

John$ ./argsc Hello World

I get a segmentation fault error. I've tried quoting the strings to no avail.

jschiwal · 06-10-2006, 08:27 PM

You probably didn't allocate space for the arguments before copying them to a target. Without the source, there is no way for me to tell if this is what you did.

I would highly recommend a book, Linux Programming by Example.
http://www.amazon.com/gp/product/013...lance&n=283155

Tinkster · 06-10-2006, 10:06 PM

Quote:

Originally Posted by YankeeFan

I'm obviously new to linux, but having fun.
I actually have a couple of questions.

1) am I missing a search function on this site? I'd like to search for an answer before spamming everyone with a repeated question.

I'd suggest looking again... there's a search-link in the middle of
the menu at the top, and a search link in the top-field of the
menu on the right.

Cheers,
Tink

Dark_Helmet · 06-10-2006, 10:49 PM

Here's a simple example:

Code:

#include <stdio.h>

int main( int argc, char *argv[] )
{
  int arg_counter;

  printf( "Executed program name: %s\n", argv[0] );

  for( arg_counter = 1; arg_counter < argc; arg_counter++ )
    printf( "argument #%d:\t%s\n", arg_counter, argv[arg_counter] );

  return 0;
}

LzW-x · 06-10-2006, 11:12 PM

is "hello world" the name of the file?

or is world the command arguement?

YankeeFan · 06-11-2006, 08:22 AM

RE: Search. Yes, I found it about 1 minute after my post. I couldn't find it because it was right in front of me. Sigh!

My code:
=====================================
#include <stdio.h>

main(int argc, char *agrv){

int i;

printf("The value of argc is %d", argc);
printf("The first command-line arg is: %s\n", argv[0]);
for( i=1; i<argc; i++ ){
printf("\n %s", argv[i]);
}
return 0;

}
======================================

I compiled it with gcc -o argsc argsc.c
This gives me argsc

The online tutorial I was looking at says all I need to do in my terminal window is enter the name of my program and my arguments. For my example, it only prints what i enter at the command line - hopefully.

I enter:
John$ ./argsc Hello World

I think I should see:
argsc Hello World

Thoughts??

I appreciate the help.