What is a typedef in C | Using typedef with structures

typedef in C:

typedef: The typedef stands for type definition. The typedef is a keyword used in C Programming to redefine names to the already existing variable. It provides a shortcut for multiple variables to declare their data type. 

Syntax of typedef in C:

    typedef  data_type  existing_name  name1,name2.....;

    typedef is a keyword used to redefine names for the existing name.

    data_type is the type of the existing_name.

    existing_name is the already given variable name.

    name1, name2,..... are the other names given to the existing variable.

Declaring typedef in C:

    typedef  int var  v1, v2;

                (or)

    typedef  int  var;

    var v1,v2;  

Note: The data type of new variables will be the existing name.    

    Both the above declarations are the same. In the above example, I have declared var as an existing name, and the v1, v2 are the redefined names of type int. In the second declaration, instead of declaring the type of v1, v2 I have declared var as its type. 

We can also write the above declaration as:

    int v1, v2;

The typedef keyword is useful when we are dealing with large data types such as structures, unions, and pointers.

Example: Let's see a simple example of a typedef keyword.

    Program:

    Output:

    Explanation: In the above example, I have declared an existing variable as a score. The redefined variables as s1 and s2. Make sure the type of new variables will be the existing name. These variables are initialized with s1=10 and s2=20.

Using typedef with structures:

Example: Let's see the structure example with typedef.

   Program: 

    Output:

   Explanation: In the above example, the typedef keyword is used to define the structure, emp is declared as a structure variable or we can call it a typedef existing name. With the help of the existing name, we have created a new name e1. BY using e1 we have initialized the structure members. We have used the dot(.) operator to access the members of the structure. 

typedef with Pointers:

Example: Let's see a simple example of typedef using pointers.

    Program:

   Output:

    Explanation: In the above example, the pointer variable ptr is declared using typedef. The redefined two pointers are p1,p2. To store the address of another variable, ma and n are initialized. Address(&) operator is used to store the location address of the variable. Indirection operator(*) is used to print the value stored at the address location.

    In this tutorial, you have learned how to create a new name for the existing name using the C typedef keyword.

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