Basic in C programming

 📑C-BASIC📑 

C Keyword

Keywords are predefined, reserved words used in programming that have special meanings to the compiler. Keywords are part of the syntax and they cannot be used as an identifier. For example:

int money;

Here, int is a keyword that indicates money is a variable of type int (integer).

As C is a casesensitive language, all keywords must be written in lowercase. 

Here is a list of all keywords allowed in ANSI C.

All these keywords, their syntax, and application will be discussed in their respective topics.

C Variabels

Variable in C is nothing but a name given to a storage area that our programs can manipulate. This location is used to hold the value of the variable, which determines the size and layout of the variable’s memory. In
C variable might be belonging to any of the data types like int, float, char etc.

Following are the rules for Naming Variables in C:

• A Variable in C name must begin with a letter or underscore.
• They are case sensitive.
• They can be constructed with digits, letters.
• No special symbols are allowed other than underscore.

Let's see the syntax to declare a variable :

data_type variable_name;

The example of declaring the variable is given below:

int a; float b; char c;

Here, a, b, c are variables. The int, float, char are the data types.

We can also provide values while declaring the variables as given below:

int a=10,b=20;//declaring 2 variable of integer type float f=20.8; char c='A';

C Data Types

Data types specify how we enter data into our programs and what type of data we enter.

Following are the examples of some very common data types used in C:

• int: As the name suggests, an int variable is used to store an integer.
• char: The most basic data type in C. It stores a single character and requires a single byte of memory in almost all compilers.
• float: It is used to store decimal numbers (numbers with floating point value) with single precision.
• double: It is used to store decimal numbers (numbers with floating point value) with double precision.

int :-

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

We can use int for declaring an integer variable.

int id;

Here, id is a variable of type integer.

You can declare multiple variables at once in C programming. For example,

int id, age;

float and double :-

float and double are used to hold real numbers.

float salary; double price;

In C, floating-point numbers can also be represented in exponential. For example,

float normalizationFactor = 22.442e2;

What's the 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.

char :-

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

char test = 'h';

The size of the character variable is 1 byte.

short and long :-

If you need to use a large number, you can use a type specifier long. Here's how:

long a; long long b; long double c;

Here variables a and b can store integer values. And, c can store a floating-point number.

If you are sure, only a small integer ([−32,767, +32,767] range) will be used, you can use short.

short d;

signed and unsigned :-

In C, signed and unsigned are type modifiers. You can alter the data storage of a data type by using them. For example,

unsigned int x; int y;

Here, the variable x can hold only zero and positive values because we have used the unsigned modifier.

Considering the size of int is 4 bytes, variable y can hold values from -231 to 231-1, whereas variable x can hold values from 0 to 232-1.