Is there API or a Refrence in VB that will allow me to quickly(as in 1 or 2 lines of code) check a string to see if another string is in it?

Example:
Im searching through these 4 lines:


aaaaaaaaaaaaaaaaa1aaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaa111aaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1


My search string is "11"

It will return the 3rd line only, since it contains my search string.

Ive seen it before but i cant find it anywhere, it was 1 line of code that would return true or false.. Thats what i need

Any help would be greatly appreciated, thank you!