如何将u8数组转换为u32？

Question

如何将u8数组转换为u32？

例如：

u8 a[4];
u32 b; 

a[0] = 0x00;
a[1] = 0x00;
a[2] = 0x00;
a[3] = 0x09;

如何将数组a（8bitx4 = 32bit）转换为b（32bit）？

Answer 1

unsigned char a[4];
unsigned int b;

a[0] = 0x00;
a[1] = 0x00;
a[2] = 0x00;
a[3] = 0x09;

int n = 1;
if (*(char *)&n == 1) {
    std::reverse(std::begin(a), std::end(a));
}

b = *reinterpret_cast<unsigned int *>(&a);