c++while控制語句

while語句結構：while(condition){

　　　　　　　　　　statement;

　　　　　　　　}

condition 表示返回值是true or false 若是返回的一直是true則statement語句則一直執行下去，直至condition爲false；

#include<iostream>
int main(){
        int sum=0,val=0;
 //只要val小於10（condition）則一直執行執行while循環內的語句
        while(val<=10){
             sum+=val; 
             ++val;//val 加1 add 1 to val   等於val=val +1;

        }    
        std::cout<<"sum of 1 to 10 is "<<sum<<std::endl;
        return 0;
}           

練習：計算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=0,val=50;
        while(val<=100){
        sum+=val;
        ++val;
        }
        cout<<"sum of 50 to 100 is "<<sum<<endl;
        return 0;
}

練習：用戶輸入兩個整數，輸出者兩個整數之間的全部整數

/*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=0,val2=0,tmp=0;
        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 0;
}