If you pass around span instead of pointer and length then it becomes less error prone and shorter - https://godbolt.org/z/Y4WqPM3r4

#include <span>

int get();

void fun(int* p, unsigned len)
{
    for ( unsigned i = 0u; i < len; ++i ) *p++ = get();
}

void more_fun(int* p, unsigned len)
{
    for (auto& e : std::span{p, len}) e = get();
}

void best_fun(std::span<int> buff)
{
    for (auto& e : buff) e = get();