For windows,
Code:
#include <stdio.h>
#include <windows.h>

int clrscr( int Colums, int Rows );

int main()
{
	int counter;
	for(counter=0; counter<35; counter++)
	{
		clrscr(0, 0);
		clrscr(counter, 0);
		printf("Weee");
		Sleep(25);
	}
	return 0;
}

int clrscr( int Colums, int Rows )
{
    	COORD coordScreen = { Colums, Rows };
    	DWORD cCharsWritten;
    	CONSOLE_SCREEN_BUFFER_INFO csbi;
    	DWORD dwConSize;
    	HANDLE hConsole = GetStdHandle(STD_OUTPUT_HANDLE);

    	GetConsoleScreenBufferInfo(hConsole, &csbi);
    	dwConSize = csbi.dwSize.X * csbi.dwSize.Y;
    	FillConsoleOutputCharacter(hConsole, TEXT(' '), 
    	dwConSize, coordScreen, &cCharsWritten);
    	GetConsoleScreenBufferInfo(hConsole, &csbi);
    	FillConsoleOutputAttribute(hConsole, csbi.wAttributes, 
    	dwConSize, coordScreen, &cCharsWritten);
    	SetConsoleCursorPosition(hConsole, coordScreen);
    	return 0;
}
Does all look good?