Check if a String contains something

Hey Guys,
Soes someone know how to check if a string has content. Like so:

void func(String foo){
if ("foo has content") {
do smth;
}}

Thx in advance

I see that you are using some language other than C. But in C it would be:

if (foo != "") {...

im using arduino thx anyway

rusus:
im using arduino thx anyway

You're welcome. Did this not work for you? Arduino uses C language.

strstr()