What is Global Variables in C?

By Anjnee Bhatnagar|Updated : October 12th, 2022

The Global Variable in C is usually declared just before the primary function. Every programming language has different variables and their usage and syntaxes to be followed to use the memory efficiently. A variable in a programming language is of significant use.

Global Variable in C PDF

We have different types of variables like local variables, static variables, and global variables in the C language. In this article, we will learn about the meaning of a variable in C programming language, the definition, syntax, example, and the use of the global variables in C.

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What is a Variable in C?

A variable is nothing but a name for a memory location. A variable also called an identifier, has a range and scope according to the data type it is mentioned for. Every variable has a data type associated with specifying the range, size, etc.

In C, there are majorly three variables based on the scope: local, static, and global. A local variable has local scope within the block it is declared in. A static variable creates memory at the compile time and retains its value throughout the program execution. A global variable is declared outside of any block or function. Now let us dive deep into the meaning of global variables in C.

What is Global Variable in C?

As the name suggests, the scope of the global variable is global, or any program member can access it. On the other hand, a local variable has local scope. The global variable in C is an important part of the GATE exam. The default value of a global variable in C is set to zero(0).

Global Variable in C Definition

A global variable in C is defined as one that is declared outside of any block or function. Any function and number of times can change the value of a global variable in the C programming language. Its value can be altered and reused many times.

Use of Global Variables in C

As we have discussed the definition of global variables, we now know they are useful. We define a global variable at the very top of the program. These variables hold their value throughout the lifetime of the program.

Any block or function in the program can access the global variables. This means that once declared, we can use global variables as often as required, and they are available for use for the entire lifetime of the program.

Syntax and Example of Global Variable in C

The syntax of a global variable is the same as any other variable declaration in C. A question can be formulated in the GATE question paper. That is data_type followed by the variable_name;


int value;

However, the global variables are declared outside of any block or function. It is declared just before the main function of the program. The declaration of the global variable will be clear by seeing the following example:

int value=9;


void main()


printf(“%d”, value);

return 0;


Output: 9

Important GATE Topics

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FAQs on Global Variables in C

  • A global variable in C is a variable that is defined outside of the supplied function. These are not limited to a single function, which means that any function can be used to not only access but also modify global variables.

  • Based on the type and scope, there are mainly three categories of variables in C language, and they are as follows:

    • Local variable: Has local scope and declared within a block of code.
    • Static variable: They create space in the memory at the compile-time only.
    • Global variables: They are declared outside of any function and contain 0 as the default value.
  • Yes, it is mandatory to declare the global variables right at the beginning of the program. Declaring at the starting makes other functions and blocks in the program easier to access the global variables.

  • As the name itself suggests the fundamental difference between the two, a local variable is declared inside a function and has the scope within the function only. In contrast, the global variables are declared outside of any function and have global scope throughout the entire execution of the program.

  • A global variable is declared outside of any function or block of code. It is declared just before the main function. It may be declared before or after the header files declaration. A global variable can be accessed globally in the program.

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