CODEWITHSUNDEEP
cfunctioninputarguments
Barak
Barak

Reputation: 43

How to add "int argc and char *argv[]" to my main function and impliment into my code?

I am working on creating an uppercase function. I want to implement argc and argv arguments in to my code but I don't know how to do it.

Here is my code;

Main.c:

#include <stdio.h>
#include <stdlib.h>

#include "upperc.h"


int main(int argc, char *argv[])
{
    char s[] = "HellO2 world3!";

    printf("%s \n", s);
    printf("%s \n", uppercase(s));

    return 0;
}

upper.c:

/*
Parsing the string, then making the letters to uppercase.
*/

#include <stdio.h>
#include "upperc.h"

char * uppercase(char *s) {
    for(char *p = s; *p; ++p) {
        if ('a' <= *p && *p <= 'z')
            *p = *p & ~' ';
    }

    return s;
}

upper.h:

#ifndef UPPERC_H_INCLUDED
#define UPPERC_H_INCLUDED

char * uppercase(char *s);

#endif // UPPERC_H_INCLUDED

Upvotes: 1

Views: 426

Answers (1)

Bodo
Bodo

Reputation: 9855

As this looks like some kind of homework, I don't give a full answer.

argc is the number of arguments including the program name that was executed. That means argc is 1 if no arguments were specified, 2 if one argument was specified etc.

Don't pass argv[1] unconditionally to your uppercase function. This would be undefined behavior if argc is 1 or even 0. (see below for details)

Depending on your requirements, you should check argc and process either only argv[1] if available, which would be the first argument, or process argv[1], argv[2] ... in a loop as necessary.

Additional details (for experts, because my original wording was not exact):

If your program is called in a normal way, the value of argc should be at least 1 and argv[0] will be the program name. The value of argv[argc] is a NULL pointer. Of course you can access the pointer value in this case, but you cannot dereference it, i.e. you cannot access a value where the pointer would be pointing to.

It is possible to call your program in a way that results in an argc value 0. In this case argv[0] will be a NULL pointer, and the array element argv[1] (and all following it) will be undefined.

See https://en.cppreference.com/w/c/language/main_function

Upvotes: 1

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