- main() function must be defined in every C program
- C program execution starts from main() function.
- main() function automatically invoke by Operating system.
- Defining other functions along with main() function.
- We must declare(prototype) of user function.
Calling the function:
- Only main() function invokes automatically by OS
- All other functions in C program must be called manually.
- User function logic executes only when we call.
The following program clearly explains how the control back to calling function after execution of called function.
Calling Function: the function from which other function called.
Called Function: the function which is called from other function.
We can invoke the function any number of times once it has defined.
- We can define any number of functions in C-Program.
- We can define the functions in any order.
- We invoke the defined functions in any order.
Execution flow of HelloWorld program briefly:
- Every C Program execution starts with main() function.
- OS invokes main() function automatically.
- #include is a pre-processor directive which is used to connect programs in C application.