YouTipC Examples Sum Prime Numbers
# C Example - Check if a Number Can Be Expressed as the Sum of Two Prime Numbers
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Check if a number can be expressed as the sum of two prime numbers.
## Example
#includeint checkPrime(int n); int main(){int n, i, flag = 0; printf("Enter a positive integer: "); scanf("%d", &n); for(i = 2; i<= n/2; ++i){// Check if if(checkPrime(i) == 1){if(checkPrime(n-i) == 1){printf("%d = %d + %dn", n, i, n - i); flag = 1; }}}if(flag == 0)printf("%d cannot be expressed as the sum of two prime numbers.", n); return 0; }// Check for prime number int checkPrime(int n){int i, isPrime = 1; for(i = 2; i<= n/2; ++i){if(n % i == 0){isPrime = 0; break; }}return isPrime; }
The output is:
Enter a positive integer: 3434 = 3 + 3134 = 5 + 2934 = 11 + 2334 = 17 + 17
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