C ++生成警告：取消引用类型标记的指针将破坏严格的别名规则

Question

I have this warning on my cast line code:

dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict- aliasing]

unsigned char buffer[64];
...
unsigned int value = *(unsigned int*)buffer;

How to fix this warning ?

Thanks for your help !

Answer 1

What this code does depends on the platform's endianness, alignment rules, integer size, and other things. There's no way to know what it does just by looking at it. But you probably want something like this:

unsigned int value = buffer[0];
value = (value << 8) | buffer[1];
value = (value << 8) | buffer[2];
value = (value << 8) | buffer[3];