Programming

Hi friends,
I have this problem that I am facing, I want to store an argument which is passed to main, and I want to store it as an array of characters. I can store number arguments with the help of x = atoi(argv[1]). Now suppose I passed the argument

Code:

Hello

to main, how can I store it somewhere in my program? I can access that "hello" through

Code:

argv[1]

but how can I store it in another variable, so that I can carry different operations on it? What can kind of variable is able to hold the value of

Code:

argv[1]

And is it only the SPACE character which seperates different arguments passed to the main, or is there any other character other than space which can act as seperator?
Looking forward to your wonderful replies.

Thanks in advance!

Code:

#include <string.h>
int main(int argc, char **argv)
{
    char arg[80]={0x0};
    strcpy(arg, argv[3]);
    printf("arg = %s\n", arg);
    return 0;
}

I think you had better dynamically allocate the memory to hold the string copy. A fixed length buffer is subject to buffer overflows. strdup(3) would do the work for you. Alternatively, you can use malloc and strcpy to do the same work.

The separator is one of the characters in the IFS variable, which can be modified to suit your needs
Note that you can still pass arguments with embedded separators by single or double quoting them.

That's only true when the program's being launched by a shell. Even then, it's the shell that does the splitting, not the program.

@Corona688: I don't get your comment unless I'm really misunderstanding the initial question.

The open poster is referring to argv so IMHO clearly asking about how parameters are split before calling the main function, not inside it.

The shell is also the usual way to launch a program and probably also the one the open poster is thinking of when referring to arguments being separated by a space character.

---------- Post updated at 21:12 ---------- Previous update was at 20:14 ----------

@gabam: about your separator question, can you clarify how you are calling your main and especially passing arguments to it. i.e. from the shell or from withing another C program ? In the latter case, with what function ?

pflynn is correct in suggesting using malloc.

However the base requirement is not reasonable. As far as I can see. You already have strings in **argv.

If you need to call them something useful like one, two and three ( you make up meaningful names) use pointers. Duplicating them serves no logical purpose except to use memory. The only time you would care about duplicating them is when both of these are true:

1. you need to keep them for later use, unchanged

2. you plan to change them (The C standard says you can modify them, you cannot tack more characters onto the end of each one, though). If you are concatenating **argv strings onto one of the **argv strings, then create duplicates.

otherwise use pointers to those strings. simple example:

Code:

#include <stdlib.h>
#include <errno.h>
int main(int argc, char **argv)
{
    char *one=argv[1];
    char *two=argv[2];
    char *three=argv[3];
    if(argc!=4)  // we want 3 parameters, as an example
    {
         errno=EINVAL;
         perror("3 parameters required, no more, no less");
         exit(1);
     }
     // do things with one, two && three 
     return 0;
}