Can I stop an if else statement if something is false?

I am new to programming and I have a form that I am trying to make. I would like to have the password validate and if it does not, then the script should stop. I have the instructions in an if else statement and I can't seem to use 'break' to make it stop. Is there a way to do this?

Here is the code:

if(isset($_POST["number"])){
if(!($_POST["number"])){
echo "Please type a password";
}
else if (($_POST["number"]) != ("W34Ut8")){
echo "Invalid password, sorry";
}
else {
echo "Password accepted";
}
}​

There is more code after this section that continues to "POST" the information from the form, however, I want the script to STOP and display the "statement" if there is no password or if the password is invalid.

Can I do that with this code I have written?

 

If you want to completely stop and exit the script you can use die( 'statment' ) or exit()

 

Oh, THANK YOU so much, the exit() worked just the way I had hoped.

Maig.