Using typedef to Substitute a Variable’s Type
C++ allows you to substitute variable types to something that you might find convenient. You use the keyword typedef for that. Here is an example where a programmer wants to call an unsigned int a descriptive STRICTLY_POSITIVE_INTEGER.
typedef unsigned int STRICTLY_POSITIVE_INTEGER; STRICTLY_POSITIVE_INTEGER numEggsInBasket = 4532;
When compiled, the first line tells the compiler that a STRICTLY_POSITIVE_INTEGER is nothing but an unsigned int. At later stages when the compiler encounters the already defined type STRICTLY_POSITIVE_INTEGER, it substitutes it for unsigned int and continues compilation.