Write a C program to find sum of all prime numbers between 1 to n using for loop. C program to generate sum of all primes between a given range. Logic to find sum of prime numbers in a given range.

**Example**

**Input**

Input upper limit: 10

**Output**

Sum of prime numbers between 1-10: 17

## Required knowledge

Basic C programming, If else, For loop, Nested loops

Must know – Program to find Prime numbers in a given range.

### What is Prime number?

Prime numbers are positive integers greater than 1 that has only two divisors 1 and the number itself. For example: 2, 3, 5, 7, 11 are the first 5 prime numbers.

## Logic to find sum of prime numbers between 1 to n

Step by step descriptive logic to find sum of prime numbers between 1 to n.

- Input upper limit to find sum of prime from user. Store it in some variable say
`end`. - Initialize another variable
`sum = 0`

to store sum of prime numbers. - Run a loop from 2 to
`end`, incrementing 1 in each iteration. The loop structure should look like`for(i=2; i<=end; i++)`

. - Inside the loop check if loop counter variable is prime or not. If
`i`is prime then add`i`to`sum`i.e.`sum = sum + i`

. - Finally after loop print the resultant value of
`sum`.

## Program to find sum of prime numbers between 1 to n

```
/**
* C program to find sum of prime numbers between 1 to n
*/
#include <stdio.h>
int main()
{
int i, j, end, isPrime, sum=0;
/* Input upper limit from user */
printf("Find sum of all prime between 1 to : ");
scanf("%d", &end);
/* Find all prime numbers between 1 to end */
for(i=2; i<=end; i++)
{
/* Check if the current number i is Prime or not */
isPrime = 1;
for(j=2; j<=i/2 ;j++)
{
if(i%j==0)
{
/* 'i' is not prime */
isPrime = 0;
break;
}
}
/*
* If 'i' is Prime then add to sum
*/
if(isPrime==1)
{
sum += i;
}
}
printf("Sum of all prime numbers between 1 to %d = %d", end, sum);
return 0;
}
```

## Program to find sum of prime numbers in given range

```
/**
* C program to find sum of prime numbers in given range
*/
#include <stdio.h>
int main()
{
int i, j, start, end;
int isPrime, sum=0;
/* Input lower and upper limit from user */
printf("Enter lower limit: ");
scanf("%d", &start);
printf("Enter upper limit: ");
scanf("%d", &end);
/* Find all prime numbers in given range */
for(i=start; i<=end; i++)
{
/* Check if the current number i is Prime or not */
isPrime = 1;
for(j=2; j<=i/2 ;j++)
{
if(i%j==0)
{
/* 'i' is not prime */
isPrime = 0;
break;
}
}
/*
* If i is Prime then add to sum
*/
if(isPrime==1)
{
sum += i;
}
}
printf("Sum of all prime numbers between %d to %d = %d", start, end, sum);
return 0;
}
```

Output

Enter lower limit: 10 Enter upper limit: 20 Sum of all prime numbers between 10 to 20 = 60

Happy coding ðŸ˜‰

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