Question

This is my code

#include <stdio.h>

void abc(char *text);

int main(void)
{
    char text[20];
    abc(text);
    printf("text in main : %s\n",text);
    return 0;
}

void abc(char *text)
{
    text = "abc";
    printf("text in abc function : %s\n",text);
}

And this is output.

text in abc function : abc
text in main : ฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬฬ๑ป ๚

My questions are:

1. Why is the text variable in the main function and in the abc function is not the same?
2. I try to change to use scanf in the abc function and it works! there are the same. Why?
3. How to modify the code to make it work. I means from question1 that make main function and in abc function are the same?

Answer 1

When you call the function:

 abc(text);

a copy of the pointer text is made, and this pointer is the one used in the function abc(). So that when you say:

text = "abc";

you are changing the copy, not the one back in main.

Also, you cannot in general assign strings in C – you have to use library functions like strcpy() instead. To make your code work, you need to change:

 text = "abc";

to:

 strcpy( text, "abc" );