C++ 14 - std :: revers(ed)std :: string在开始时是否包含空字符？

Question

如果我std::reverse在std::string变量上使用,我可以安全地假设空字符'\0'将放在字符串的开头吗？

Answer 1

不,它不包含NUL字节(除非你把它放在那里).前向迭代器也不包含NUL字节,它只会遍历字符串本身的字符.

但是,保证NUL字节超过.c_str()或结束.data().

示例程序:

#include <string>
#include <iostream>
#include <algorithm>

int main() {
    std::string s = "Hello";
    std::cout << "Forwards:\n";
    for (auto i = std::begin(s), e = std::end(s); i != e; ++i) {
        std::cout << *i << ' ' << static_cast<int>(*i) << '\n';
    }
    std::cout << "Backwards:\n";
    std::reverse(std::begin(s), std::end(s));
    for (auto i = std::begin(s), e = std::end(s); i != e; ++i) {
        std::cout << *i << ' ' << static_cast<int>(*i) << '\n';
    }
    return 0;
}

输出:

Forwards:
H 72
e 101
l 108
l 108
o 111
Backwards:
o 111
l 108
l 108
e 101
H 72