c++while控制语句

while语句结构：while(condition){

　　　　　　　　　　statement;

　　　　　　　　}

condition 表示返回值是true or false 如果返回的一直是true则statement语句则一直执行下去，直至condition为false；

#include<iostream>
int main(){
        int sum=,val=;
 //只要val小于10（condition）则一直执行执行while循环内的语句
        while(val<=){
             sum+=val;
             ++val;//val 加1 add 1 to val   等于val=val +1;
        }
        std::cout<<"sum of 1 to 10 is "<<sum<<std::endl;
        return ;
}           

练习：计算50到100的和；

//write a program that uses a while to sum the numbers from 50 to 100
#include<iostream>
using namespace std;
int main(){
        int sum=,val=;
        while(val<=){
        sum+=val;
        ++val;
        }
        cout<<"sum of 50 to 100 is "<<sum<<endl;
        return ;
}

练习：用户输入两个整数，输出者两个整数之间的所有整数

/*write a program that prompts the user for two intergers,print each number in the range specified by those two interger*/
#include<iostream>
using namespace std;
int main(){
        int val1=,val2=,tmp=;
        cout<<"Enter the first number: ";
        cin>>val1;
        cout<<"Enter the second number:";
        cin>>val2;
        if(val1>val2){
        tmp=val1;
        val1=val2;
        val2=val1;
        }
        while(val1<=val2){
                tmp=val1;
                ++val1;
                cout<<tmp<<endl;
        }
        return ;
}