当有某一个变量，你不知道他是什么类型，且你有需要知道他是什么类型时，就可以使用typeid关键字进行判断！
操作如下：
判断int类型
int in = 10;
if (typeid(in) == typeid(int)) {
cout << "This '" << in << "' is a int!" << endl;
}
判断类
// 类
Student stu("小明");
if (typeid(stu) == typeid(Student)) {
cout << "This '" << stu.name << "' is a Student!" << endl;
}
当然你也还可以 判断其它类型这里就不列举了！
来说说具体改怎么使用：
double dou = 3.14;
if (typeid(dou) == typeid(int)) {
cout << "This '" << dou << "' is a int!" << endl;
} else if (typeid(dou) == typeid(string)) {
cout << "This '" << dou << "' is a string!" << endl;
} else if (typeid(dou) == typeid(double)) {
cout << "This '" << dou << "' is a double!" << endl;
} else {
cout << "This '" << dou << "' is not!" << endl;
}
用法如上，使用多个if else做逻辑处理，就可以得到想要的变量是什么类型了！
全部测试代码：
#include
#include
using namespace std;
class Student {
public:
Student(string _name = "无名字") {
this->name = _name;
}
~Student() { }
public:
string name;
};
typedef struct Struct {
int count = 10;
};
int main(void) {
// 整形
int in = 10;
if (typeid(in) == typeid(int)) {
cout << "This '" << in << "' is a int!" << endl;
}
// 字符串
string str = "abc";
if (typeid(str) == typeid(string)) {
cout << "This '" << str << "' is a string!" << endl;
}
// 字符
char c = 'c';
if (typeid(c) == typeid(char)) {
cout << "This '" << str << "' is a char!" << endl;
}
// 类
Student stu("小明");
if (typeid(stu) == typeid(Student)) {
cout << "This '" << stu.name << "' is a Student!" << endl;
}
// 结构体
typedef struct Struct structs;
if (typeid(structs) == typeid(Struct)) {
cout << "This 'structs' is a Struct!" << endl;
}
double dou = 3.14;
if (typeid(dou) == typeid(int)) {
cout << "This '" << dou << "' is a int!" << endl;
} else if (typeid(dou) == typeid(string)) {
cout << "This '" << dou << "' is a string!" << endl;
} else if (typeid(dou) == typeid(double)) {
cout << "This '" << dou << "' is a double!" << endl;
} else {
cout << "This '" << dou << "' is not!" << endl;
}
return 0;
}
运行截图：
总结：
用法还是很简单的，不过，我这里只是简单将typeid关键字的其中一个用法列举出来，其实他还有很多其它高级用法， 有兴趣的可以自行去了解了解！