According to this link: String concatenation
I think this line should be OK:
String x = "Start pumpe " + p + " !"; // p is an Int !!!!!!!!
but no, no, this error message comes up:
invalid operands of types 'const char*' and 'const char ' to binary 'operator+'
I wonder it should be sophisticated to concatenate a string !
I know there is other ways to do it - but why not use the easy one - is there an error here or what's wrong ?