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=0,val=0; //只要val小于10(condition)则一直执行执行while循环内的语句 while(val<=10){ 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 0; }
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=0,val=50; while(val<=100){ sum+=val; ++val; } cout<<"sum of 50 to 100 is "<<sum<<endl; return 0; }
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=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; }