2.1.2节练习

2.3

unsigned u=10,u2=42;std::cout<<u2-u<<std::endl;  //输出  32std::cout<<u-u2<<std::endl;   // 输出4294967264int i=10,i2=42;std::cout<<i2-i<<std::endl;  //  32std::cout<<i-i2<<std::endl;  //-32std::cout<<i-u<<std::endl;   // 0std::cout<<u-1<<std::endl;   // 02.4正确