C :

#include<stdio.h>
#include<math.h>
int main()
{
	int i,j,s=0;
	for(i=100;i<=200;i++)
	{
		for(j=2;j<=sqrt(i);j++)
		{
			if(i%j==0)break;
		}
		if(j>sqrt(i)){s++;if(s==1)printf("%d",i);else printf(" %d",i);};
	}
	return 0;
}

C++ :

#include <iostream>  
#include<cmath>                            //在Dev C++中可调用数学函数库cmath
using namespace std;
int main ()
{
  int x;
  for (int i=100;i<=200;++i)
  {
     x=2;
     while(x<=floor(sqrt(i))&&(i%x!=0))    //floor为取整函数，需调用math.h库
     x=x+1;                       //在枚举的范围内并且没有出现约数则继续枚举
     if ( x>floor(sqrt(i)))
       cout<<i<<" ";
  }
  return 0;
}