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如果构造函数只接受一个实参，则它实际上定义了转换为此类类型的隐式转换机制。将这种构造函数称为转换构造函数。
#ifndef MAIN_H_INCLUDED#define MAIN_H_INCLUDED#include <iostream>using namespace std;class ClassTest{public:ClassTest(){cout << "ClassTest()" <<endl;}ClassTest(int i){cout << "ClassTest(int)" <<endl;value = i;value2 = 2;}ClassTest(int i, int j): value(i), value2(j){cout << "ClassTest(int, int)" <<endl;}ClassTest(const ClassTest& test){cout << "ClassTest(const ClassTest&)" << endl;value = test.value;value2 = test.value2;}void getValue(int &, int &);private:int value = 0;int value2 = 0;};#endif // MAIN_H_INCLUDED
#include "main.h"void ClassTest::getValue(int &iValue, int &iValue2){iValue = value;iValue2 = value2;}int main(){ClassTest classTest = 2;/*** 还可以使用以下几种实现方法* ClassTest classTest(2);* ClassTest classTest = ClassTest(2);* ClassTest classTest = (ClassTest)2;*/int value = 0;int value2 = 0;classTest.getValue(value, value2);cout << "value = " << value << "\nvalue2 = " << value2 << endl;return 0;}
#ifndef MAIN_H_INCLUDED#define MAIN_H_INCLUDED#include <iostream>using namespace std;class ClassTest{public:ClassTest(){cout << "ClassTest()" <<endl;}ClassTest(string str){strValue = str;}string getValue(){return strValue;}private:string strValue;};#endif // MAIN_H_INCLUDED
#include "main.h"int main(){ClassTest classTest = string("Hello world!");//ClassTest classTest = "Hello world!";/*无法实现从char[]先转化为string，在由string转换为类类型*/cout << classTest.getValue() << endl;return 0;}
#ifndef MAIN_H_INCLUDED#define MAIN_H_INCLUDED#include <iostream>using namespace std;class ClassTest{public:ClassTest(){cout << "ClassTest()" << endl;}/*** 如果是在类声明之外进行类成员函数的实现，explicit只加在声明的位置*/ClassTest(string str){strValue = str;}string getValue(){return strValue;}private:string strValue;};#endif // MAIN_H_INCLUDED
#include "main.h"int main(){//ClassTest classTest = string("Hello world!");/**< 错误 */ClassTest classTest(string("hello world"));/**< 只能用于直接初始化 *///ClassTest classTest = "Hello world!";/*无法实现从char[]先转化为string，在由string转换为类类型*/cout << classTest.getValue() << endl;return 0;}
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原文地址：http://www.cnblogs.com/fengkang1008/p/4652252.html
