What real use does a double pointer have? [closed]

Answer 1

It's less used in c++. However, in C, it can be very useful. Say that you have a function that will malloc some random amount of memory and fill the memory with some stuff. It would be a pain to have to call a function to get the size you need to allocate and then call another function that will fill the memory. Instead you can use a double pointer. The double pointer allows the function to set the pointer to the memory location. There are some other things it can be used for but that's the best thing I can think of.

int func(char** mem){
    *mem = malloc(50);
    return 50;
}

int main(){
    char* mem = NULL;
    int size = func(&mem);
    free(mem);
}