Question

How to allocate dynamic memory inside a function with C

Answer 1

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

int* f(int*);

int main()
{
    int n = 90;
    int* p;
    
    p = f(p); 
    n = *p;
    
    free(p);

    printf("n = %d", n);
    
    return 0;
}

int* f(int* p) {
    p = (int*)malloc(sizeof(int));
    *p = 320;
    
    return p; 
}




/*
run:

n = 320

*/

 

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Answer 2

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

int* f(int**);

int main()
{
    int n = 90;
    int* p;
    
    p = f(&p); 
    n = *p;
    
    free(p);

    printf("n = %d", n);
    
    return 0;
}

int* f(int** p) {
    *p = (int*)malloc(sizeof(int));
    **p = 320;
    
    return *p; 
}



/*
run:

n = 320

*/

 

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