C++ switch语句后表达式的类型，vs2015试过

VS2015试过short,int, long,long long, bool, char,signed char,unsigned char,wchar_t，整型变量的引用可以。
但float，double，long double,char[],指向整型的指针，string不行.

#include<iostream>using namespace std;int main() {    short a=2;    int b=2;    long c=2;    long long d=2;    int *u = &b;    int &r = b;    int cnt = 0;    float e=1.20;    double f=1.34;    long double g=3.4;    bool h=1;    char i='a';    signed char m='b';    unsigned char n='c';    char w[3] = {'1','2','3'};    wchar_t j='w';    enum num {one,two}s;    s = one;    string str;    switch (str) {    case 1: ++cnt; break;    case 0: ++cnt; break;    default: break;    }    return 0;}