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Reputation: 13

Passing a pointer from a function to another function

I am looking for a way to pass a pointer from not main function to another function. A variable x with value 5 sends as pointer to func1, func1 changes variable value to 10, then func1 sends same variable to func2.

I want it to look something like that:

#include <stdio.h>

void func1(int *px);
void func2();

int main(void)

{   
    int x=5;
    printf("x in main %d\n", x);
    func1(&x);

    return 0;
}

void func1(int *px)
{
    *px = 10;
    printf("x i funk 1 %d\n", *px);
    funk2(); // send to this function a pointer to x, which in this function(func1) is pointed by *px
    funk3();
}

void func2()
{
    //*px=15 // here I want to change value of x 
}

Upvotes: 1

Views: 3461

Answers (2)

Stephen Docy
Stephen Docy

Reputation: 4788

Simply pass the argument in func1() to func2(), as a pointer, px in func1() and py in func2() will point to the same memory location, the address of x.

int main(void)

{
    int x = 5;
    printf("x in main %d\n", x);
    func1(&x);

    printf("x now %d\n", x);

    return 0;
}

void func2(int *py)
{
    *py = 15; // here I want to change value of x 
}



void func1(int *px)
{
    *px = 10;
    printf("x in funk 1 %d\n", *px);
    func2(px); // send to this function a pointer to x, which in this function(func1) is pointed by *px

}

output:

x in main 5
x in funk 1 10
x now 15

Upvotes: 1

Pablo
Pablo

Reputation: 13580

I am completely lost in how to do that.

Using the exact same logic you used for passing the pointer to x from main to func1.

In this case func2 should also accept a pointer to intand func1 should pass the pointer to func2 that it got from main:

#include <stdio.h>

void func1(int *px);
void func2(int *px);

int main(void)

{   
    int x=5;
    printf("x in main %d\n", x);
    func1(&x);

    // x will be 15 here

    return 0;
}

void func1(int *px)
{
    *px = 10;
    printf("x i funk 1 %d\n", *px);
    funk2(px); // send to this function a pointer to x, which in this function(func1) is pointed by *px
    //funk3(); // this function was not defined anywhere
}

void func2(int *px)
{
    *px=15;
}

Upvotes: 1

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