C Programming Data Types

In C programming, variables or memory locations should be declared before it can be used. Similarly, a function also needs to be declared before use.

Data types simply refers to the type and size of data associated with variables and functions.

Data types in C

1. Fundamental Data Types
• Integer types
• Floating type
• Character type


2. Derived Data Types
• Arrays
• Pointers
• Structures
• Enumeration

int - Integer data types

Integers are whole numbers that can have both positive and negative values but no decimal values. Example: 0, -5, 10

In C programming, keyword int is used for declaring integer variable. For example:

int id;

Here, id is a variable of type integer.

You can declare multiple variable at once in C programming. For example:

int id, age;

The size of int is either 2 bytes(In older PC's) or 4 bytes. If you consider an integer having size of 4 byte( equal to 32 bits), it can take 2³² distinct states as: -2³¹,-2³¹+1, ...,-2, -1, 0, 1, 2, ..., 2³¹-2, 2³¹-1. If you try to store larger number than 2³¹-1, i.e,+2147483647 and smaller number than -2³¹, i.e, -2147483648, program will not run correctly.

Similarly, int of 2 bytes, it can take 2¹⁶ distinct states from -2¹⁵ to 2¹⁵-1.

float - Floating types

Floating type variables can hold real numbers such as: 2.34, -9.382, 5.0 etc. You can declare a floating point variable in C by using either float or double keyword. For example:

float accountBalance;
double bookPrice;

Here, both accountBalance and bookPrice are floating type variables.

Difference between float and double

The size of float (single precision float data type) is 4 bytes. And the size of double (double precision float data type) is 8 bytes. Floating point variables has a precision of 6 digits whereas the precision of double is 14 digits.

char - Character types

Keyword char is used for declaring character type variables. For example:

char test = 'h';

Here, test is a character variable. The value of test is 'h'.

The size of character variable is 1 byte.