C程序计算间隔倍数

Question

How to write a program that calculates the multiples of 7 between 21 and 210 inclusive? This is an incorrect example:

finding multiples of 7

#include<stdio.h>

int main(){

int multiple;
int sum;
int i=0;
int j=0;
int sum1,sum2;


for (i=1;i>=21;i++){
    printf(i);
    sum1=i+sum1;

    for(j=1;j<=210;j++){
        printf(j);
        sum2=j+sum2;
    }
}
sum=sum1+sum2;
printf("sum",sum);
 }

Answer 1

Define lower and upper limit as n1 and n2 with 21 and 210 respectively.

#include <iostream>
#include <stdio.h>

int main()
{
    int n1,n2;
    n1=21;
    n2=210;
    while(n1<=n2)
    {
        if(n1%7==0)
            printf("%d ",n1);
        n1=n1+1;
    }
}

Tested code on Code Chef - https://www.codechef.com/ide

Output:

21 28 35 42 49 56 63 70 77 84 91 98 105 112 119 126 133 140 147 154 161 168 175 182 189 196 203 210

Answer 2

Try this:

#include<stdio.h>

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

    //set your lower bound and upper bound
    for (i = 21 ; i <= 210 ; i++)
    {
        if ( (i % 7) == 0 )
        {
            sum += i;
        }
    }

    printf("total sum = %d \n",sum);
 }

Answer 3

main()
{
  for(int n = 21; n<=210; n+=7)
    printf("%d", n);
}