Published by: Zaya
Published date: 17 Jun 2021
A header file is a file containing C declarations and macro definitions (see Macros) to be shared between several source files. You request the use of a header file in your program by including it, with the C preprocessing directive ‘ #include ‘. Header files serve two purposes.
Your request to use a header file in your program by including it with the C preprocessing directive #include, like you have seen the inclusion of stdio.h header file, which comes along with your compiler.
Including a header file is equal to copying the content of the header file but we do not do it because it will be error-prone and it is not a good idea to copy the content of a header file in the source files, especially if we have multiple source files in a program.
A simple practice in C or C++ programs is that we keep all the constants, macros, system-wide global variables, and function prototypes in the header files and include that header file wherever it is required.
Operators are symbols that tell to program-specific mathematical or logical operations. Operators are used to operating the operand. Programming languages typically support a set of operators. There are different types of operators in the C programming language.
Arithmetic operator
The arithmetic operator is used to perform the mathematical calculation. C contains five arithmetic operators.
Example:
| Operators | Meaning | Example |
| + | Addition | a+b |
| – | Subtraction | a-b |
| * | Multiplication | a*b |
| / | Division | a/b |
| % | Modules | a%b |
Relational operator
The relational operator determines the relationship between two different operands. It is also known as a comparison operator, which can be used to check the condition. It always returns a true or false result.
Example:
| Operators | Meaning | Example |
| < | Less than | a |
| <= | Less than or equal | a<=b |
|
>
|
Greater than | a>b |
| >= | Greater than or equal | a>=b |
| == | Equal to | a==b |
| != | Not equal to | a!=b |
Assignment operator
An assignment operator assigns the value of an expression to an identifier.
Example:
| Operators | Meaning | Example |
| = | assign | A=5+6 |
Logical operator
Logical operators are used to calculating logical expressions. It accepts two or more inputs and produces a single output.
Example:
| Operators | Meaning | Example |
| $$ | Logical AND | (a>b)$$(a>c) |
| || | Logical OR | (a>b)||(a>c) |
| ! | Logical NOT | a!=b |
Comma operator
C allows us to put multiple expressions in the same statement separated by a comma.
Example: a,b;
Ternary operators
An expression that makes use of the conditional operator is called a ternary operator.
Example: (a>b)? true:false
Input-Output Statement
An input/output statement or IO statement is a portion of a program that instructs a computer on how to read and process information. It pertains to gather information from an input device or sending information to an output device. Input, Output, Programming terms.