替换 O/iStream 布尔位移运算符

Question

我想替换 i/ostream 的位移布尔重载。当前实现仅接受"0"或"1"的输入字符串，仅输出"0"或"1"。我想做一个布尔重载，考虑其他序列，如"t"，"true"，"f"，"false"等......有没有办法这样做，即使它仅限于有限的范围？这是我要使用的代码：

inline std::ostream& operator << (std::ostream& os, bool b)
{
    return os << ( (b) ? "true" : "false" );
}
inline std::istream& operator >> (std::istream& is, bool& b)
{
    string s;
    is >> s;
    s = Trim(s);
    const char*  true_table[5] = { "t", "T", "true" , "True ", "1" };
    const char* false_table[5] = { "f", "F", "false", "False", "0" };
    for (uint i = 0; i < 5; ++i)
    {
        if (s == true_table[i])
        {
            b = true;
            return is;
        }
    }
    for (uint i = 0; i < 5; ++i)
    {
        if (s == false_table[i])
        {
            b = false;
            return is;
        }
    }
    is.setstate(std::ios::failbit);
    return is;
}

Answer 1

如果你愿意放弃t并f作为可能性，你可以使用std::boolalpha和std::noboolalpha

从 CPP 首选项：

// boolalpha output
std::cout << std::boolalpha 
          << "boolalpha true: " << true << 'n'
          << "boolalpha false: " << false << 'n';
std::cout << std::noboolalpha 
          << "noboolalpha true: " << true << 'n'
          << "noboolalpha false: " << false << 'n';
// booalpha parse
bool b1, b2;
std::istringstream is("true false");
is >> std::boolalpha >> b1 >> b2;
std::cout << '"' << is.str() << "" parsed as " << b1 << ' ' << b2 << 'n';

输出：

boolalpha true: true
boolalpha false: false
noboolalpha true: 1
noboolalpha false: 0
"true false" parsed as 1 0