String Manipulation in Function

programming flash
1

I’m using a function to call multiple button actions, so I don’t have to rewrite code for each button… here’s the script:

function btnSelect(num){
	var btnA = "btn" + num;
	btnA.onRelease = function(){
		if (loaded == filesize) {
		picture._alpha = 0;
		picture.loadMovie(image[num], 1);
		desc_txt.text = description[num];
		picture_num();
		}
	}
}
btnSelect("0");
btnSelect("1");
btnSelect("2");
btnSelect("3");
btnSelect("4");

This is all part of a clip which loads pictures externally… each of the buttons (which are mc’s) are named btn0, btn1, etc… any ideas how to make this work??