从 std::ostream 获取 char*

可以使用流插入运算符 "<<" 以及流对象的成员函数 str() 来获取 char*。例如：

std::ostringstream os;
os << "Hello world!";
std::string str = os.str();
const char* charPtr = str.c_str();

在上述代码中，我们使用 std::ostringstream 对象 os 来将字符串输出到流中，然后使用 str() 函数将流对象转化为 std::string 对象，最后使用 c_str() 函数获取 std::string 对象内部存储的 char* 指针。

相关问题

[Error] cannot bind 'std::ostream {aka std::basic_ostream<char>}' lvalue to 'std::basic_ostream<char>&&'

这个错误是因为尝试将一个左值绑定到一个右值引用上，具体来说是尝试将一个 std::ostream 对象绑定到一个 std::basic_ostream<char>&& 上。这通常发生在使用移动语义时，例如将一个 std::ostream 对象传递给一个接受右值引用的函数。解决方法是使用 std::move() 将左值转换为右值引用。

[Error] cannot bind ‘std::ostream {aka std::basic_ostream＜char＞}‘ l value To'std::basic_ostream<char>&&'

This error message means that you are trying to assign a value to an output stream (std::ostream) using an lvalue (an expression that refers to an object that has a memory address) but the type of the lvalue is not compatible with the type of the output stream.

For example, if you have the following code:

int main() {
    int x = 42;
    std::ostream out;
    out = x;
    return 0;
}

You will get the error message because you cannot assign an integer value to an output stream. You need to use the insertion operator (<<) to write the value to the stream:

int main() {
    int x = 42;
    std::ostream out;
    out << x;
    return 0;
}

This will write the value of x to the output stream.