为什么 sprintf 只转换了我的 uint64_t 数据的一半？

Question

#include <iostream>



using namespace std;

int main()
{
    uint64_t a = 0xffffffffffffffff;
    int c = 3;
    char b[16];
    sprintf(b, "%X", a);
    cout << b << endl;
    return 0;
}

This is printing and storing half of the fs, i need the rest of them, how do i do this?

Answer 1

You are invoking undefined behavior by passing data having wrong type.

The type format to print uint64_t in uppercase hex is PRIX64 , defined in the header <cinttypes> .

Also don't forget to allocate for terminating null-character.

#include <iostream>
#include <cstdio>    // sprintf()
#include <cinttypes> // PRIX64 (and its family) is defined in this header



using namespace std;

int main()
{
    uint64_t a = 0xffffffffffffffff;
    int c = 3;
    char b[17]; // allocate also for terminating null-character
    sprintf(b, "%" PRIX64, a); // use correct format
    cout << b << endl;
    return 0;
}