Programming Fundamentals/Typedef - An Alias

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

General Discussion[edit | edit source]

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 Variables[edit | edit source]

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 Variables[edit | edit source]

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.

Definitions[edit | edit source]

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