相关疑难解决方法(0)

在阅读了有关签名/未签名比较的问题之后(我每隔几天就会说出来):

• 签名/未签名比较和-Wall

我想知道为什么我们没有正确的签名无符号比较,而是这个可怕的混乱？从这个小程序中获取输出:

#include <stdio.h>
#define C(T1,T2)\
 {signed   T1 a=-1;\
 unsigned T2 b=1;\
  printf("(signed %5s)%d < (unsigned %5s)%d = %d\n",#T1,(int)a,#T2,(int)b,(a<b));}\

 #define C1(T) printf("%s:%d\n",#T,(int)sizeof(T)); C(T,char);C(T,short);C(T,int);C(T,long);
int main()
{
 C1(char); C1(short); C1(int); C1(long); 
}

用我的标准编译器(gcc,64bit)编译,我得到这个:

char:1
(signed  char)-1 < (unsigned  char)1 = 1
(signed  char)-1 < (unsigned short)1 = 1
(signed  char)-1 < (unsigned   int)1 = 0
(signed  char)-1 < (unsigned  long)1 = 0
short:2
(signed short)-1 < (unsigned  char)1 = 1
(signed short)-1 < (unsigned short)1 = 1
(signed short)-1 < …