C++ explicit

explicit關鍵字的用途:用來修飾建構函式避免隱式轉換。

 

#include <iostream>
using namespace std;
class a
{
public:
        a(int c){b = c;};
        void show(){cout << b << endl;};
private:
        int b;
};
int main()
{
        a bb = 1;
        bb.show();
        return 0;
}

運行結果：

[root@localhost tmpc++]# ./s7
1

 

#include <iostream>
using namespace std;
class a
{
public:
        explicit a(int c){b = c;};
        void show(){cout << b << endl;};
private:
        int b;
};
int main()
{
        a bb = 1;
        bb.show();
        return 0;
}

運行結果：

[root@localhost tmpc++]# g++ s7.cpp  -o s7
s7.cpp: In function ‘int main()’:
s7.cpp:13: 錯誤：請求從‘int’轉換到非標量類型‘a’