2、ile语句时,应注意几个问题。示例1示例2while循环语句(续)使用while语句时,应注意以下几个问题:(1)while语句的特点是“先判断,后执行”。(2)循环体由多个语句组成时,必须用{}号括起来,使其构成一复合语句。如下例:voidmain(){inti,sum;i=5;sum=0;while(i>0){sum=sum+i;i--;}}(3)循环必须有结束条件,以免“死循环”。while循环语句示例例1:利用while语句实现:从键盘输入n(n>0)个数,求其之和。程序:voidmain(){inti,n,k,sum
3、;i=1;sum=0;printf("Inputn:");scanf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++;}printf("sumis:%d",sum);}运行:isum10while循环语句示例程序:voidmain(){inti,n,k,sum;i=1;sum=0;printf("Inputn:");scanf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++;}printf("sumis:%d
4、",sum);}运行:isum10Inputn:例1:利用while语句实现:从键盘输入n(n>0)个数,求其之和。while循环语句示例程序:voidmain(){inti,n,k,sum;i=1;sum=0;printf("Inputn:");scanf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++;}printf("sumis:%d",sum);}运行:isum10Inputn:3例1:利用while语句实现:从键盘输入n(n>0)个数,求其之和。while循
5、环语句示例程序:voidmain(){inti,n,k,sum;i=1;sum=0;printf("Inputn:");scanf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++;}printf("sumis:%d",sum);}运行:isum10Inputn:312例1:利用while语句实现:从键盘输入n(n>0)个数,求其之和。while循环语句示例程序:voidmain(){inti,n,k,sum;i=1;sum=0;printf("Inputn:");sc
6、anf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++;}printf("sumis:%d",sum);}运行:isum112Inputn:312例1:利用while语句实现:从键盘输入n(n>0)个数,求其之和。while循环语句示例程序:voidmain(){inti,n,k,sum;i=1;sum=0;printf("Inputn:");scanf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++;}printf
7、("sumis:%d",sum);}运行:isum212Inputn:312例1:利用while语句实现:从键盘输入n(n>0)个数,求其之和。while循环语句示例程序:voidmain(){inti,n,k,sum;i=1;sum=0;printf("Inputn:");scanf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++;}printf("sumis:%d",sum);}运行:isum212Inputn:31234例1:利用while语句实现:从键
8、盘输入n(n>0)个数,求其之和。while循环语句示例程序:voidmain(){inti,n,k,sum;i=1;sum=0;printf("Inputn:");scanf("%d",&n);while(i<=n){scanf("%d",&k);sum=sum+k;i++