C :

#include<stdio.h>
int prime(int n)
{
	for(int i = 2; i * i <= n; i++)
		if(n % i == 0)
			return 0;
		return 1;
}
int main()
{
	int i, N;
	scanf("%d", &N);
	for(i = 2; i <= N; i++)
		if(prime(i))
			printf("%d\n", i);
		return 0;
}

C++ :

#include<stdio.h>
#include<stdlib.h> 
int main()
{
    int n;
    scanf("%d",&n);
    static char a[10000000];
    unsigned long k,i;
    for(k=2;k<=10000;k++)
        if(!a[k])
            for(i=2*k;i<n;i+=k)
               a[i]=1;
    for(i=2;i<n;i++)
        if(!a[i])
    {
        printf("%ld\n",i);
    }
    return 0;
}

Pascal :

var a,b,n,k:longint;
begin
  readln(n);
  for a:=1 to n do
  begin
    k:=0;
    for b:=1 to a do
    if a mod b=0 then k:=k+1;
    if k=2 then writeln(a);
  end;
end.