Argument Processing

[Daniel Rudy]

Hello,

I'm trying to learn how command line arguments are handled in C. The
following code segment that I wrote as a test program compiles, but when
I try to run it, it core dumps. This is under a FreeBSD environment.
What am I doing wrong here?

/*

just echos the command line arguments onto the screen
tests the format of argument processing

*/

#include <stdio.h>
#include <string.h>
int main(int argc, char argv[])
{
int i; /* generic counter */

printf("argc = %d", argc);
for (i = 0; i <= argc; i++)
{
printf("argv[%d] = %s\n", i, argv[i]);
}

/* return to operating system */
return(0);
}
--
Daniel Rudy

Email address has been encoded to reduce spam.
Remove all numbers, then remove invalid, email, no, and spam to reply.

[Jack Klein]

On Fri, 05 Nov 2004 05:41:31 GMT, Daniel Rudy
<i0************ *************** *******@n0o1p2a 3c4b5e6l7l8s9p0 a1m2.3n4e5t6>
wrote in comp.lang.c:

Hello,

I'm trying to learn how command line arguments are handled in C. The
following code segment that I wrote as a test program compiles, but when
I try to run it, it core dumps. This is under a FreeBSD environment.
What am I doing wrong here?

/*

just echos the command line arguments onto the screen
tests the format of argument processing

*/

#include <stdio.h>
#include <string.h>
int main(int argc, char argv[])
{
int i; /* generic counter */

printf("argc = %d", argc);
for (i = 0; i <= argc; i++)
Replace "<=" with "<" in the loop. argv[argv] is a null pointer.
{
printf("argv[%d] = %s\n", i, argv[i]);
}

/* return to operating system */
return(0);
Note that 'return' is a statement, not a function. Parentheses do no
harm, but have not been required since the first ANSI standard 15
years ago.
}

--
Jack Klein
Home: http://JK-Technology.Com
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[Ravi Uday]

"Daniel Rudy"
<i0************ *************** *******@n0o1p2a 3c4b5e6l7l8s9p0 a1m2.3n4e5t6>
wrote in message news:fo******** *********@newss vr14.news.prodi gy.com...

Hello,

I'm trying to learn how command line arguments are handled in C. The
following code segment that I wrote as a test program compiles, but when
I try to run it, it core dumps. This is under a FreeBSD environment.
What am I doing wrong here?

/*

just echos the command line arguments onto the screen
tests the format of argument processing

*/

#include <stdio.h>
#include <string.h>
int main(int argc, char argv[])
{
int i; /* generic counter */

printf("argc = %d", argc);
for (i = 0; i <= argc; i++)
{
printf("argv[%d] = %s\n", i, argv[i]);
}

/* return to operating system */
return(0);
}
What are you passing to main from command line ?
You might try adding this before the first printf.

if ( argc < 3 )
{
printf ("Insufficie nt arguments to main\n");
return 0;
}
- Ravi


--
Daniel Rudy

Email address has been encoded to reduce spam.
Remove all numbers, then remove invalid, email, no, and spam to reply.

[Satyajit]

Daniel Rudy wrote:

#include <stdio.h>
#include <string.h>
int main(int argc, char argv[])
{
int i; /* generic counter */

printf("argc = %d", argc);
for (i = 0; i <= argc; i++)
Rewrite this as
for (i = 0; i < argc; i++)
{
printf("argv[%d] = %s\n", i, argv[i]);
}

/* return to operating system */
return(0);
}

Satyajit
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[wangxiaopeng1976]

I think the problem is the declareation of the main function,
should be :
int main(int argc, char* argv[])

also should modify the <= to <

[E. Robert Tisdale]

Daniel Rudy wrote:

I'm trying to learn how command line arguments are handled in C.
The following code segment that I wrote as a test program compiles
but when I try to run it, it core dumps.
This is under a FreeBSD environment.
What am I doing wrong here?
[snip]
cat main.c /*
*
* just echos the command line arguments onto the screen
* tests the format of argument processing
*
* */

#include <stdio.h>
#include <string.h>
int main(int argc, char* argv[]) {

printf("argc = %d\n", argc);
for (int i = 0; i < argc; ++i) {
printf("argv[%d] = %s\n", i, argv[i]);
}

/* return to operating system */
return 0;
}
gcc -Wall -std=c99 -pedantic -o main main.c
./main arg1 arg2 arg3 argc = 4
argv[0] = ./main
argv[1] = arg1
argv[2] = arg2
argv[3] = arg3 gcc --version gcc (GCC) 3.4.2 uname -o Darwin man 3 getopt

GETOPT(3) BSD Library Functions Manual GETOPT(3)

NAME
getopt - get option character from command line argument list

LIBRARY
Standard C Library (libc, -lc)

SYNOPSIS
#include <unistd.h>

extern char *optarg;
extern int optind;
extern int optopt;
extern int opterr;
extern int optreset;

int
getopt(int argc, char * const *argv, const char *optstring);

[Mac]

On Fri, 05 Nov 2004 00:01:59 -0600, Jack Klein wrote:

... argv[argv] is a null pointer.

Of course you mean argv[argc] is a null pointer.

--Mac

[Mike Wahler]

"Daniel Rudy"
<i0************ *************** *******@n0o1p2a 3c4b5e6l7l8s9p0 a1m2.3n4e5t6>
wrote in message news:fo******** *********@newss vr14.news.prodi gy.com...

Hello,

I'm trying to learn how command line arguments are handled in C. The
following code segment that I wrote as a test program compiles, but when
I try to run it, it core dumps. This is under a FreeBSD environment.
What am I doing wrong here?
See below.
/*

just echos the command line arguments onto the screen
tests the format of argument processing

*/

#include <stdio.h>
#include <string.h>
int main(int argc, char argv[])
int main(int argc, char *argv[])

/* or */

int main(int argc, char **argv)
{
int i; /* generic counter */

printf("argc = %d", argc);
for (i = 0; i <= argc; i++)
for (i = 0; i < argc; i++)

{
printf("argv[%d] = %s\n", i, argv[i]);
}

/* return to operating system */
return(0);
}

-Mike

[surend2k]

no problem with the declartion it is fine

[Mike Wahler]

<su******@yahoo .com> wrote in message
news:10******** ************@c1 3g2000cwb.googl egroups.com...

no problem with the declartion it is fine

Look again. It's not.

-Mike