C Foundation

What is C? C Compiler Installation C Extensions C Compiler C Interpreter C Program Structure

C Basics

C Keywords C Data Types C Identifiers C Variables C Constant C Escape Sequences C Constant and Volatile C Typecast

Operators

What is Operator C Comma Operator C Arithmetic Operators C Relational Operators C Logical Operators C Bitwise Operators C Conditional Operators C : : Operator C Operator Priority

Basic IO's

Basic IO's C Formatted Functions C Unformatted Functions C Common Functions

Control Statements

What is Control Statement C if Statement C if else Statement C Nested if Statement C Else if Statement C Break Statement C Continue Statement C Switch Statement C Goto Statement

Looping

What is Control Loop C for Loop C Nested for Loop C while Loop C Nested while Loop C do while Loop C Nested do while loop

Functions

What is Function C User Defined Functions C Recursion C Passing Parameters

Scope

Scope C Local Scope C Global Scope

Storage Classes

What is Storage Class C Auto C Extern C Static C Register

Array

What is Array C One Dimensional Array C Two Dimensional Array C Multi Dimensional Array C Arrays Of Strings

String

What is String C String Functions

Pointer

What is Pointer C Pointers Arithmetic C Pointer to Pointer C Pointers and Arrays C Pointers and Strings C Pointer to Functions Void Pointers Null Pointers C Null and Void Pointer

Structure

What is Structure C Struct within Struct C Array within Structure C Pointer to Structure C Structure and Function C Enum C Bitfield Structure C Type def

Union

What is Union

Files

What is File C read a file C write a file C File Handling C Error Handling C Low Level Disk I/O C Other file functions

Memory Allocation

What is Memory Allocation C Malloc() C Calloc() C Free() C Realloc() C Coreleft()

C Reference

All ASCII Code Basic C Questions

C Interview

C Interview Sets All Star Patterns All Number Patterns All Alphabet Patterns All Series Patterns
The ones who are crazy enough to think they can change the world are the ones who do.
- Steve Jobs

C Variables

What Is Variables?

Generally, Variables are things which are all changable. We encounter several variables in our day-to-day life.

Example

  • Time is variable which changes for every single seconds.
  • Climate is variable which changes as per season.
  • Rheostat is variable which changes to increase or to decrease circuit resistance.
  • Speed is variable, either one can accelerate to increase the speed or decelerate to decrease the speed.
C Variables

Variables in C

In C programming, variable is an identifier for a memory location for storing data. Once data is stored with a variable name, it can be retrieved by its variable name for various computations in a C program. A data that can be changed by assigning a new data to the variable. Variable can be numerical quantity or character constant.

Variable Purpose

Different operations can be performed using data stored in variables during program execution Such opereations are Addition, Subtraction, Mutiplication etc

A data can be accessed later in the program by simply referring the name of the variable.

Rules for declaring Variables

  • Variable name should not be a C keyword.
  • Variable must be declared before it can be used.
  • Variable name should not be starts with a digit.
  • Variable name may be a combination of UPPERCASE and lowercase. e.g.) firstName
  • Variable name cannot be repeated within the same scope.
  • A data type (int, float, char) is established when the variable is defined. Once defined the type of variable cannot be changed

Variables C Program

variables.c
#include <stdio.h>
int main()
{
int number = 25;
int Number = 47;
printf("The number is %d ",number);
printf("\nThe Number is %d ",Number);
return 0;
}
  • The number is 25
  • The Number is 47

Note:

The values 25 and 47 are stored in a memory location with its unique variable name number and Number respectively.

Helpful Tips

  • Variable can be declared at the start of block of code which is more helpful for later reference
  • Variable name may be declared based on the meaning of the operation. e.g.) result, average, sum etc.

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