"Header File" in C/C++

Introduction of Header file :-

A header file in programming is a file that contains declarations of functions. It acts as a bridge between your implementation code and the compiler.

Let's Understand with this simple example (C++ Code):-

#include<iostream>
using namespace std;
int main(){
int num1,num2,sum;
cout<<"Enter first number: ";
cin>>num1;
cout<<"Enter second number: ";
cin>>num2;
sum=num1+num2;
cout<<"The sum of "<<num1<<" and "<<num2<<"="<<sum;
return 0;
}

Output:-

Enter first number: 12 

Enter second number: 34

The sum of 12 and 34 = 64

how to write in C/C++ Header File:-

# Include :-

These prevent the header file from being included multiple times in the same source file, which could lead to compilation errors due to duplicated declarations.

Library Includes:-

If your header file relies on external libraries or other header files, you might need to include them to ensure that the declarations work properly.

Forward Declarations:- 

These are used to declare classes, functions, or variables that are used in the interface but defined elsewhere.

Type Definitions:- 

If your header file introduces custom data types, typedefs, they should be declared here.

Function Declarations:-

Declare functions that are part of the interface but defined in separate implementation files. This lets other source files use these functions without needing to know the implementation details.

Class/Struct Declarations:- 

If your header defines classes or structs, provide the class/struct declarations without the implementation details.

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