signed C++ · 关键字

有符号整型说明符，表示该整型可以表示正数、负数和零；单独使用时等价于 signed int。

怎么用

signed 类型 名;

小例子

signed char c = -1;
std::cout << (int)c;

运行结果

-1

提醒：signed char、short、int、long、long long 默认就是有符号的，显式写 signed 更常见于 char

官方文档：https://en.cppreference.com/w/cpp/language/types