Programming Fundamentals/Typedef - An Alias

An explanation of typedef being used to create an alias data type.

General DiscussionEdit

The typedef statement allows the programmer to create an alias, or synonym, for an existing data type. This can be useful in documenting a program. The C++ programming language syntax is:

typedef <the real data type> <the alias identifier name>;

Let's say a programmer is using a double data type to store the amount of money that is being used for various purposes in a program. He might define the variables as follows:

Example 1: Regular Definition of VariablesEdit

double  income;
double  rent;
double  vacation;

However, he might use the typedef statement and define the variables as follows:

Example 2: Using typedef when Defining VariablesEdit

typedef double cash;
    the typedef must be defined before its use
cash  income;
cash  rent;
cash  vacation;

The typedef statement is not used very often by beginning programmers. It usually creates more confusion than needed, thus stick to using the normal data types at first.

DefinitionsEdit

typedef
Allows the programmer to create an alias, or synonym, for an existing data type.