most used algorithm for primes generation is added

sieve_for_prime.cpp

@@ -0,0 +1,34 @@
+//sieve method is used in many questions to generate prime numbers.
+//its beauty is its low complexity i.e O(n*log(log(n)))
+
+
+#include <bits/stdc++.h> 
+using namespace std; 
+
+void SieveOfEratosthenes(int n) 
+{ 
+	bool prime[n+1]; 
+	memset(prime, true, sizeof(prime)); 
+
+	for (int p=2; p*p<=n; p++) 
+	{ 
+		if (prime[p] == true) 
+		{ 
+			for (int i=p*p; i<=n; i += p) 
+				prime[i] = false; 
+		} 
+	} 
+
+	for (int p=2; p<=n; p++) 
+	if (prime[p]) 
+		cout << p << " "; 
+} 
+
+int main() 
+{ 
+	int n;
+	cout<<"Enter the value upto which you want prime numbers";
+	cin>>n;
+	SieveOfEratosthenes(n); 
+	return 0; 
+}