#include<iostream>
#include<cctype>
using std::cin;
using std::cout;
using std::endl;
int main()
{
    int num1=0;
    int num2=0;
    double average=0;
    int yes_no=0;
    int count=0;
    while(std::tolower(yes_no)!='n')
    {
        cout<<"Enter a number please"<<endl;
             cin>>num1;
             num2+=num1;
             count++;
             cout<<"Do you want to enter anoter number"<<"("<<"y/n"<<")"<<endl;
             cin>>yes_no;
             cout<<endl;
    }
         average=num2/count;
    cout<<"The plused number is"<<num2<<endl;
    cout<<"The average number is"<<average<<endl;
    return 0;
}
        当输入了Y后进入死循环，cin语句不能正常执行非常郁闷。请帮忙解说下，我也能用其他语句解决，但是不知道为什么这样就不行。高手帮忙

你tolower的用法不对啊...
它的声明为:
int tolower( int c );
而且也不在STD里啊..

其实你只要把yes_no声明为char就行了,何必那么麻烦...

#include<iostream>
#include<cctype>
using std::cin;
using std::cout;
using std::endl;
int main()
{
    int num1=0;
    int num2=0;
    double average=0;
    int yes_no=0;
    int count=0;
    while(yes_no!='n'）
    {
        cout<<"Enter a number please"<<endl;
             cin>>num1;
             num2+=num1;
             count++;
             cout<<"Do you want to enter anoter number"<<"("<<"y/n"<<")"<<endl;
             cin>>yes_no;
             cout<<endl;
    }
         average=num2/count;
    cout<<"The plused number is"<<num2<<endl;
    cout<<"The average number is"<<average<<endl;
    return 0;
}
不用tolower 也不对啊，跳不出循环

#include<iostream>
#include<cctype>
using std::cin;
using std::cout;
using std::endl;
int main()
{
    int num1=0;
    int num2=0;
    double average=0;
    int yes_no=0;
    int count=0;
    while(yes_no!='n'）
    {
        cout<<"Enter a number please"<<endl;
             cin>>num1;
             num2+=num1;
             count++;
             cout<<"Do you want to enter anoter number"<<"("<<"y/n"<<")"<<endl;
             cin>>yes_no;
             cout<<endl;
    }
         average=num2/count;
    cout<<"The plused number is"<<num2<<endl;
    cout<<"The average number is"<<average<<endl;
    return 0;
}
不用tolower 也不对啊，跳不出循环

#include<iostream>
#include<cctype>
using std::cin;
using std::cout;
using std::endl;
int main()
{
    int num1=0;
    int num2=0;
    double average=0;
    char yes_no='\0';//////////char
    int count=0;
    while(yes_no!='n')
    {
        cout<<"Enter a number please"<<endl;
             cin>>num1;
             num2+=num1;
             count++;
             cout<<"Do you want to enter anoter number"<<"("<<"y/n"<<")"<<endl;
             cin>>yes_no;
             cout<<endl;
    }
         average=num2/count;
    cout<<"The plused number is"<<num2<<endl;
    cout<<"The average number is"<<average<<endl;
    return 0;
}

都说要改char了....
这次要是跳不出来就是有鬼....

为什么要改成CHAR那为什么int 就不行啊？？

能说明下吗，char和int不过是占用字节大小不同为很么会影响到循环哪？？

你试一下:
int a;
cin>>a;
cout<<a<<endl;
//////////////////////
你输入一个n,看看输出是什么?
另外,要知道字符的比较实际是比较ACCIS码
n的ACCIS码是110
你要是再不明白,我就没办法了...

明白了，谢谢拉。