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Write a C++ Program to Check Whether a Number can be Express as Sum of Two Prime Numbers
PROGRAM:C++ Program to Check Whether a Number can be Express as Sum of Two Prime Numbers
/* C++ Program to Check Whether a Number can be Express as Sum of Two Prime Numbers */
#include <iostream>
using namespace std;
bool check_prime(int n);
int main() {
int n, i;
bool flag = false;
cout << “Enter a positive integer: “;
cin >> n;
for(i = 2; i <= n/2; ++i) {
if (check_prime(i)) {
if (check_prime(n – i)) {
cout << n << ” = ” << i << ” + ” << n-i << endl;
flag = true;
}
}
}
if (!flag)
cout << n << ” can’t be expressed as sum of two prime numbers.”;
return 0;
}
// check prime number
bool check_prime(int n) {
int i;
bool is_prime = true;
// 0 and 1 are not prime numbers
if (n == 0 || n == 1) {
is_prime = false;
}
for(i = 2; i <= n/2; ++i) {
if(n % i == 0) {
is_prime = false;
break;
}
}
return is_prime;
}
