C/C++中unsigned char和char的区别

代码：

 1 #include <cstdio>
 2 #include <iostream>
 3
 4 using namespace std;
 5
 6 int main(){
 7
 8     unsigned char c1 = 0x80;
 9     char c2 = 0x80;
10     int a1 = c1;
11     int a2 = c2;
12     cout<<a1<<endl<<a2<<endl;
13
14     return 0;
15 }

输出：

128
-128

分析：

由输出可知，unsigned char向int转换时不会扩展最高位，而char（signed char）则会。