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; 

如何到阵列的（8bitx4 = 32位）至b（32位）转换？

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);