例27求1+2+3+ ■■■口■ n 输入一个正整数n,求前n项和,即循环n次 include <stdio h> int main (void) int i, sum: printf(Enter n: ) scanf(%d",&n); sum = 0: for(i=1;i<=100;i++) for(i=1; i<=n; i++) sum= sumt I sum=sumtI printf(sum=%d\n",sum) return 0: Enter n: 100 sum=5050输入一个正整数n，求前n项和，即循环n次 #include <stdio.h> int main(void) { int i, sum; sum = 0; for ( i = 1; i <= 100; i++ ) sum = sum + i; printf( “sum = %d\n”, sum); return 0; } 例2-7 求 1+2+3+……+n for(i=1; i<=n; i++) sum=sum+i; printf(“Enter n:"); scanf("%d", &n); Enter n: 100 Sum = 5050