Printing prime numbers from 1 through 100

Question

This c++ code prints out the following prime numbers: 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97.

But I don\'t think tha

Answer 1

Just try this. It's easy without any extra builtin functions.

#include 

int prime(int n,int r){

  for(int i=2;n<=r;i++){
    if(i==2 || i==3 || i==5 || i==7){
      std::cout<

Testing by 2,3,5,7 is good enough for up to 120, so 100 is OK.

There are 25 primes below 100, an 30 below 121 = 11*11.