C程序--从键盘输入n ，计算1+2+3+.....+n 的值

法一：for语句#include <stdio.h>#include <stdlib.h>main(){int n,i,sum = 0;printf("please input number ");scanf("%d",&n);for( i = 1 ; i <= n ; i++){sum +=...

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问答

町棠棠

37404人浏览 · 2020-03-16 00:15:45

町棠棠 · 2020-03-16 00:15:45 发布

法一：for语句
#include <stdio.h>
#include <stdlib.h>
 main()
{
   int n,i,sum = 0;
   printf("please input number ");
   scanf("%d",&n);
   for( i = 1 ; i <= n ; i++)
   {
       sum += i ;
   }
   printf("the sum is %d\n",sum);

}

法二：while 
#include <stdio.h>
#include <stdlib.h>
 main()
{
   int n,i=0,sum = 0;
   printf("please input number ");
   scanf("%d",&n);
   while(i <= n)
   {
       sum += i;
       i++;
   }
    printf("the sum is %d",sum);
}



法三：do-while
#include <stdio.h>
#include <stdlib.h>
 main()
{
   int n,i=0,sum = 0;
   printf("please input number ");
   scanf("%d",&n);
   do
   {
       sum += i;
       i++;
   }while(i <= n);
    printf("the sum is %d",sum);
}