What is a functions in c

Standard library functions

The standard library functions are built-in functions in C programming.
These functions are defined in header files. For example,
  • The printf() is a standard library function to send formatted output to the screen (display output on the screen). This function is defined in the stdio.h header file.
    Hence, to use the printf() function, we need to include the stdio.h header file using #include <stdio.h>.
  • The sqrt() the function calculates the square root of a number. The function is defined in the math.h header file.  

ser-defined function

You can also create functions as per your need. Such functions created by the user are known as user-defined functions.

How user-defined function works?

#include <stdio.h>
void functionName()
{
    ... .. ...
    ... .. ...
}

int main()
{
    ... .. ...
    ... .. ...

    functionName();
    
    ... .. ...
    ... .. ...
}
The execution of a C program begins from the main() function.

The control of the program jumps back to the main() function once code inside the function definition is executed.
How function works in C programming?
Note, function names are identifiers and should be unique.











































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