相关疑难解决方法(0)

什么是复制省略？什么是(命名)返回值优化？他们意味着什么？

它们会在什么情况下发生？有什么限制？

• 如果您引用了这个问题,那么您可能正在寻找介绍.
• 有关技术概述,请参阅标准参考.
• 在这里查看常见案例.

#include <cstdio>
#include <string>

void fun(const char* c)
{
    printf("--> %s\n", c);
}

std::string get()
{
    std::string str = "Hello World";
    return str;
}

int main() 
{
    const char *cc = get().c_str();
    // cc is not valid at this point. As it is pointing to
    // temporary string internal buffer, and the temporary string
    // has already been destroyed at this point.
    fun(cc);

    // But I am surprise this call will yield valid result.
    // It seems that the returned …

class Complex
{
private:
double real;
double imag;

public:
// Default constructor
Complex(double r = 0.0, double i = 0.0) : real(r), imag(i) {}

// A method to compare to Complex numbers
bool operator == (Complex rhs) {
   return (real == rhs.real && imag == rhs.imag)? true : false;
}
};

int main()
{
// a Complex object
Complex com1(3.0, 0.0);

if (com1 == 3.0)
   cout << "Same";
else
   cout << "Not Same";
 return 0;
}

输出:相同

为什么这段代码输出为Same,转换构造函数如何在这里工作,请解释一下,非常感谢提前