Question

提问： C语言如何运算 1+2+3+4+5+6+7+8+9.......+n的这种式子

Answer 1

#include <stdio.h>

void main()
{
int i, num, sum = 0;

printf("Enter an integer number \n");
scanf ("%d", &num);
for (i = 1; i <= num; i++)
{
sum = sum + i;
}
printf ("Sum of first %d natural numbers = %d\n", num, sum);
}