C :

#include<stdio.h>
void PrintLine( int X )
{
	int i;
	for( i = 0; i < X; ++i )
		putchar( '*' );
	putchar( '\n' );
	return;	
}
int main( int argc, char **argv )
{
	int n;
	scanf( "%d", &n );
	PrintLine( n );
	PrintLine( n );
	return 0;
	
}

C++ :

//输入两行n列的星号.cpp
#include<iostream>
using  namespace  std;
int  main()
{
     int n;
     cin>>n;
     for(int i=1;i<=n;i++){cout<<'*';}
     cout<<endl;
     for(int i=1;i<=n;i++){cout<<'*';}
     cout<<endl;
     return  0;
}