Undefined Offset Truppentool PHP: Undefined Index & Undefined Offset Errors?

PHP: Undefined Index & Undefined Offset errors? - undefined offset truppentool

Can someone help me with what a "Undefined index" error in PHP. The other day my site was fine, but when I opened it today originated with a load of these errors. As the lines of the errors occur in all of them contain a $ _POST to do so at guessing the problem with that.

I also get an "Undefined offset" error when you use the following code:

if ($ errors [0] == NULL) (
)

I wanted to examine only whether the first position in the womb has no value.

Thank you for your help.