c++ - 如何将uint32_t数字转换为char [8]？

Question

假设我们有一个string s = "453acd0f"。现在我想做这样的事情:

uint32_t res = 0;
for (size_t i = 0; i < 8; ++i) {
    res |= ConvertCharToHexNumber(s[8 - i - 1]) << (i * 4);
}

但是，如果我有一个从二进制文件读取的uint32_t var变量，该怎么办？

Answer 1

将4字节uint32_t转换为char[8]的最简单方法:

    uint32_t var = 100;
    char res[8]{};
    res[0] = (var >> 28) & 0XF;
    res[1] = (var >> 24) & 0XF;
    res[2] = (var >> 20) & 0XF;
    res[3] = (var >> 16) & 0XF;
    res[4] = (var >> 12) & 0XF;
    res[5] = (var >> 8)  & 0XF;
    res[6] = (var >> 4)  & 0XF;
    res[7] = (var >> 0)  & 0XF;

您可以将其简化为循环:

    int shiftby = 32;
    for (int i = 0; i < 8; i++) {
        res[i] = (var >> (shiftby -= 4)) & 0xF;
    }