Question

How do i make a dynamically allocated memory as a global memory location?

#include <stdio.h>
#include <string.h>
char* call(int);
char *y;

int main() {
    char *a;
    int x;
    x=45;
    a=call(x); \\ I guess it must be pointing to the Memory pointed by y
    printf(a); \\prints hello world
    x=46;
    strcpy(a,"good");
    a=call(x);
    printf(a);
}

char* call(int x) {
    y=(char *)malloc(40);
    if(x==45) {
        strcpy(y,"hello world");
        return(y);
    } else {
        return(y);
    }
}

I have some questions:

1. Does the memory alloacted by the malloc() stay until the end of program or until the end of the function where it is defined?

2. How do I make a and y point to the same address allocated by the malloc function when they are in different functions?

3. How do I make the dynamically allocated memory globally accessible?

Answer 1

1. Till the end of the program, or till you call free on that pointer
2. a = y; will make a and y point to the same memory location. In your case, a = call(x); does that too. a points to the memory you allocated in call which is still valid in main.
3. You’ve just done that.

Remember to free(a); in your main.