mixture of int and float in a string ?

Using Arduino Programming Questions
#1

i want to println to the serial port a series of numbers seperated by a comma

eg "1,2,3,4,1.1234567890"

when i try to concatenate the numbers together into a string it fails on the last number (1.1234567890)

is says "conversion from 'float' to 'const String' is ambiguous"

is it possible to create a string that is a mixture of integers and floating numbers ?

#2

A string or a String?

#3