add primary code

primtallYey/p.c

@@ -0,0 +1,35 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <math.h>
+
+bool checkPrime(int p, int *pptr){
+  int sqrt_p = sqrt(p);
+  for(int i = 0; i < sqrt_p; i++){
+    if(p % *(pptr+i) == 0){return false;}
+  }
+  return true;
+}
+
+int main(){
+  double max = pow(10,7);
+  int pi_max = (int)(ceil(1.1*(max/log(max))));
+  int primes[pi_max];
+  primes[0] = 2;
+  int *pptr = &primes[0];
+  int count = 1;
+
+  //calculate primes 
+  for(int c = 3; c <= max; c+=2){
+    if(checkPrime(c, pptr)){
+      primes[count] = c;
+      count++;
+    }
+  }
+
+  //print primes
+  printf("The set of all primes below %d is: ", (int)max);
+  for (int i = 0; i < count; i++){
+    printf("%d ", primes[i]);
+  }
+  return 0;
+}