C语言练习小代码

1.求 1+2+3+4+…+100 的总和？

# include <stdio.h> int main(void) { int i; int sum = 0; //sum的英文意思是“总和” for (i = 1; i <= 100; ++i) //++是自加的意思, ++i相当于i = i + 1 { sum = sum + i; /*等价于sum += i;但是不建议这么写, 因为sum = sum + i看起来更清楚、更舒服*/ } printf("sum = %d\n", sum); return 0; }

运行结果为：5050

2.求 1 到 100 之间所有奇数的和？

# include <stdio.h> int main(void) { int i; int sum = 0 ; for (i=1; i<100; i+=2) //i+=2;等价于i = i + 2; { sum = sum + i; } printf("sum = %d\n", sum); return 0; }

S3.求 1! + 2! + 3! + ... + n!

# include <stdio.h> int main(void) { int n = 0; int i = 0; int m = 1; int sum = 0; printf("请输入n的值:"); scanf("%d", &n); for (i = 1; i <= n; ++i) { m = m * i; sum = sum + m; } printf("sum = %d\n", sum); return 0; }