Something like the following. Also you need to give what language you are using. Anyways, you should be able to convert this to your language of choice.
<script type="text/javascript">
function checkGeneration() {
var gen = ["Baby Boomer ","Generation X","Xennials","Generation Y"];
var reversestr = "";
var getyear = window.prompt("Enter a 3 digit number: ");
if (parseInt(getyear) <= 1964) {
alert(gen[0]);
} else if(parseInt(getyear) <= 1979) {
alert(gen[1]);
} else if(parseInt(getyear) <= 1985) {
alert(gen[2]);
} else if(parseInt(getyear) <= 1995) {
alert(gen[3]);
}
}
checkGeneration();
</script>
