How to use "Form" command in TString class

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What is the meaning of the “Form” command in the class TString?
like this:

string cut_s=name+Form(">%f",lower)+"&&"+name+Form("<%f",upper);

Form as the same syntax as the printf command in C (search on the web).
Imagine you have a variable lower like:

float lower = 12345.;



will be the string :