C语言左移32-0位的坑

在编程中需要生成地址池以及掩码，发现一个极其隐秘的坑，希望大家引以为戒。

C语言左移32-0位的坑

源码

#include int main() {   unsigned char ucLength=0;   unsigned int  mask=0;   ucLength=0;   mask = ((0xffffffff)<<(32-ucLength));     printf("[32-0:F]0x%08x\n",mask);   mask = ((0xffffffff)<<(32));     printf("[32:F]0x%08x\n",mask);     printf("===========\n",mask);      mask = 1<<(32-ucLength);     mask--;   printf("[32-0:1]0x%08x\n",mask);    mask = 1<<(32);     mask--;   printf("[32:1]0x%08x\n",mask);  }

输出

[32-0:F]0xffffffff [32:F]0x00000000 =========== [32-0:1]0x00000000 [32:1]0xffffffff