In C programming, a variable is a named location in memory that is used to store data of a specific type. A variable can be assigned a value at any point in the program, and its value can be changed as needed.
To declare a variable in C programming, you must specify its name and type.
The syntax for declaring a variable is as follows:
type variable_name;
Here, type is the data type of the variable, such as int, float, double, char, etc., and variable_name is the name you give to the variable.
For example:
int age;
This creates a variable named age of type int.
You can also initialize a variable with a value at the time of declaration, like this:
int age = 20;
This creates a variable named age of type int and initializes it with the value 20.
Variables can be used in expressions.
For example:
int x = 10;
int y = 20;
int z = x + y; // z is now 30
In this example, the variable z is assigned the value of the expression x + y, which adds the values of x and y.
Variable data types:
C programming supports several data types for variables, including integer types (such as int, short, long, and unsigned), floating-point types (such as float and double), character types (such as char), and more complex types (such as arrays, structures, and pointers).
Size of a variable:
You can also use the sizeof operator to determine the size of a variable in bytes.
For example, the following code prints the size of an int variable in bytes:
printf("Size of int variable: %d bytes\n", sizeof(int));
In C programming, variable names must follow certain rules:
- Variable names can contain letters (uppercase and lowercase), digits, and underscores.
- The first character of a variable name must be a letter or underscore.
- Variable names cannot contain spaces or special characters (such as #, $, %, etc.).
- Variable names are case-sensitive, so myVar and myvar are considered two different variable names.
- Variable names should be descriptive and meaningful.
Most asked questions on Variables in C:
Q: What is a variable in C programming?
A: A variable is a named location in memory that is used to store data of a specific type in C programming.
Q: How do you declare a variable in C programming?
A: To declare a variable in C programming, you must specify its name and type. The syntax for declaring a variable is as follows: type variable_name;
Q: What are the different data types available for variables in C programming?
A: C programming supports several data types for variables, including integer types (such as int, short, long, and unsigned), floating-point types (such as float and double), character types (such as char), and more complex types (such as arrays, structures, and pointers).
Q: How do you initialize a variable in C programming?
A: You can initialize a variable with a value at the time of declaration by using the following syntax: type variable_name = value; For example, to initialize an integer variable called myInt with the value 10, you would use the following code: int myInt = 10;
Q: How do you access the value of a variable in C programming?
A: You can access the value of a variable by using its name in an expression. For example, to add two integer variables x and y and store the result in a third variable z, you would use the following code: int z = x + y;
Q: Can the value of a variable be changed in C programming?
A: Yes, the value of a variable can be changed as needed in C programming. You can assign a new value to a variable by using the assignment operator =. For example, to change the value of an integer variable myInt to 20, you would use the following code: myInt = 20;
Q: How do you determine the size of a variable in C programming?
A: You can use the sizeof operator to determine the size of a variable in bytes. For example, the following code prints the size of an int variable in bytes: printf(“Size of int variable: %d bytes\n”, sizeof(int));
MCQs on Variables in C Programming:
Which of the following is NOT a valid C variable name?
a. my_var
b. _myVar
c. 2var
d. MyVar2
Answer: c. 2var
What is the data type of the variable in the following C declaration: float price;
a. Integer
b. Floating point
c. Character
d. Double
Answer: b. Floating point
What is the value of the variable i after the following C code is executed: int i = 5; i += 2;
a. 5
b. 2
c. 7
d. Undefined
Answer: c. 7
Which of the following is NOT a valid way to initialize a C variable?
a. int i = 5;
b. float f = 3.14;
c. char c = ‘A’;
d. string s = “hello”;
Answer: d. string s = “hello”; (strings in C are initialized with character arrays)
What is the size of the int data type in C?
a. 2 bytes
b. 4 bytes
c. 6 bytes
d. Depends on the platform
Answer: d. Depends on the platform. However, in most modern systems, it is 4 bytes.
Which of the following is a valid C constant?
a. const float PI = 3.1415;
b. final int MAX_VALUE = 100;
c. #define MY_CONSTANT 42
d. static char* MESSAGE = “Hello World”;
Answer: a. const float PI = 3.1415;
What is the scope of a variable declared inside a function in C?
a. Global
b. Local
c. Static
d. Dynamic
Answer: b. Local
Which of the following is the correct way to declare a pointer to an integer in C?
a. int* ptr;
b. ptr int;
c. ptr* int;
d. int ptr;
Answer: a. int* ptr;
Which of the following is NOT a valid way to pass arguments to a C function?
a. Pass by value
b. Pass by reference
c. Pass by pointer
d. Pass by copy
Answer: d. Pass by copy
What is the keyword used to declare a structure in C?
a. typedef
b. struct
c. union
d. enum
Answer: b. struct