typedef in C/C++ [Quiz Included]

In this tutorial, we will discuss:

• typedef in C/C++
• Syntax of typedef in C/C++
• Examples of typedef in C/C++
• Difference between #define and typedef

After completing this tutorial, all your concepts involving #define and typedef would be crystal clear.

What is typedef in C and C++?

As the name itself suggests, typedef stands for “type definition”. typedef is nothing but a way to assign a new name to a pre-existing data type. In other words, typedef is basically a reserved keyword that we use in order to create an alias name for a specific data type.

The function performed or purpose served by the data type remains the same. We simply use it to reduce the complexity of the code for the programmer’s convenience, while declaring higher-level data types like structures and unions.

Get a Complete Overview of Data Types in C Programming Language

Syntax of typedef

The syntax of C typedef is as simple as its use.

typedef data_type new_data_type_name;

For instance,

typedef signed int positive_integer;

After assigning the alternative name for signed int, we have to use positive _integer as a data type while naming identifiers for our program.

How can we use typedef in C?

Here is a code in C which illustrates the use of typedef:

#include<stdio.h>
int main()
{

printf("Welcome to DataFlair tutorials!\n\n");

typedef signed positive_int; // Use of typedef keyword
positive_int number = 80;

printf("The number is: %d\n",number);
return 0;
}

Code on Screen-

Output-

How can we use typedef in C++?

Here is a code in C++ which illustrates the use of typedef:

#include <iostream>
using namespace std;
int main()
{
cout<<"Welcome to DataFlair tutorials!"<<endl<<endl;
typedef signed positive_int; // Use of typedef keyword
positive_int number = 80;
cout<<"The number is: "<< number <<endl;
return 0; 
}

Code-

Output-

Example of typedef in C

Now that it is pretty clear as to what typedef is, let us consider a simple problem at hand to acknowledge its significance.

Suppose, we are expected to create a structure named student with details such as name and age, instead of writing the keyword struct followed by its structure name, we could use an alternative name in order to maintain the clarity of the code. A good programmer knows what to use and how to increase the readability of the code.

Here is a code in C which illustrates the use of typedef with reference to the above-stated problem:

#include<stdio.h>

typedef struct student
{
char name[30];
int age;
}stud; // Note that stud is not an object, it is an alternative name for structure data type

int main( )
{
stud s; // s is an object of the structure

printf("Welcome to DataFlair tutorials!\n\n");

printf("Enter student name: ");
scanf("%s", s.name);

printf("Enter student age: ");
scanf("%d", &s.age);

printf("Student name is: %s\n", s.name);
printf("Student age is: %d\n", s.age);
return 0;
}

Code on Screen-

Output-

Example of typedef in C++

Here is a code in C++ which illustrates the use of typedef with reference to the above-stated problem:

#include<iostream>
using namespace std;
typedef struct student
{
string name;
int age;
}stud; // Note that stud is not an object, it is an alternative name for structure data type
int main( )
{
stud s; // s is an object of the structure
cout<<"Welcome to DataFlair tutorials!"<<endl<<endl;
cout<<"Enter student name: "<<endl;
cin>>s.name;
cout<<"Enter student age: "<<endl;
cin>>s.age;
cout<<"Student name is: "<< s.name <<endl;
cout<<"Student age is: "<< s.age <<endl;
return 0; 
}

Code- 

Output-

Difference Between typedef and #define

If you don’t even have the slightest bit of idea as to what #define is, refer to Macros. We already know that #define is a C preprocessor directive. Since both typedef and #define are used to provide alternative names to existing types, what is the difference between the two?

Here is a table that illustrates the difference between typedef and #define

Quiz on typedef in C

Summary

In this tutorial, we discussed the basic meaning behind the typedef in detail and inferred that it is nothing but an alternative name assigned to an existing data type. Then, we discussed its basic syntax and significance that helped us infer how easy and convenient it is to use a typedef. Finally, we concluded our discussion by understanding the key difference between typedef and #define.

Now, it’s time to learn Functions in C language

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