Dev C++ Void Function
Apr 28, 2019 This definition of void in C and C gives three usages of void for computer programmers. This definition of void in C and C gives three usages of void for computer programmers. A Guide to 'Void' in Computer Programming. The void function call is a stand-alone statement. C: Function Pointers We've previously talked about pointers to data structures and class objects, however in C we can also have pointers to functions. These pointers behave a little bit differently that the other pointers we've come across so far, but by the end of this tutorial you should know how to use function pointers, as well as knowing the basics of what you can and cannot do with them.
A function is a block of statements that performs a specific task. Suppose you are building an application in C language and in one of your program, you need to perform a same task more than once. In such case you have two options –
a) Use the same set of statements every time you want to perform the task
b) Create a function to perform that task, and just call it every time you need to perform that task.
Using option (b) is a good practice and a good programmer always uses functions while writing codes in C.
Types of functions
1) Predefined standard library functions – such as puts(), gets(), printf(), scanf() etc – These are the functions which already have a definition in header files (.h files like stdio.h), so we just call them whenever there is a need to use them.
2) User Defined functions – The functions that we create in a program are known as user defined functions.
In this guide, we will learn how to create user defined functions and how to use them in C Programming
Why we need functions in C
Functions are used because of following reasons –
a) To improve the readability of code.
b) Improves the reusability of the code, same function can be used in any program rather than writing the same code from scratch.
c) Debugging of the code would be easier if you use functions, as errors are easy to be traced.
d) Reduces the size of the code, duplicate set of statements are replaced by function calls.
Syntax of a function
return_type: Return type can be of any data type such as int, double, char, void, short etc. Don’t worry you will understand these terms better once you go through the examples below.
function_name: It can be anything, however it is advised to have a meaningful name for the functions so that it would be easy to understand the purpose of function just by seeing it’s name.
argument list: Argument list contains variables names along with their data types. These arguments are kind of inputs for the function. For example – A function which is used to add two integer variables, will be having two integer argument.
Block of code: Set of C statements, which will be executed whenever a call will be made to the function.
Do you find above terms confusing? – Do not worry I’m not gonna end this guide until you learn all of them :)
Lets take an example – Suppose you want to create a function to add two integer variables.
Let’s split the problem so that it would be easy to understand –
Function will add the two numbers so it should have some meaningful name like sum, addition, etc. For example lets take the name addition for this function.
This function addition adds two integer variables, which means I need two integer variable as input, lets provide two integer parameters in the function signature. The function signature would be –
The result of the sum of two integers would be integer only. Hence function should return an integer value – I got my return type – It would be integer –
So you got your function prototype or signature. Now you can implement the logic in C program like this:
How to call a function in C?
Consider the following C program
Example1: Creating a user defined function addition()
Output:
Example2: Creating a void user defined function that doesn’t return anything
Output:
Few Points to Note regarding functions in C:
1) main() in C program is also a function.
2) Each C program must have at least one function, which is main().
3) There is no limit on number of functions; A C program can have any number of functions.
4) A function can call itself and it is known as “Recursion“. I have written a separate guide for it.
C Functions Terminologies that you must remember
return type: Data type of returned value. It can be void also, in such case function doesn’t return any value.
Note: for example, if function return type is char, then function should return a value of char type and while calling this function the main() function should have a variable of char data type to store the returned value.
Structure would look like –
More Topics on Functions in C
1) Function – Call by value method– In the call by value method the actual arguments are copied to the formal arguments, hence any operation performed by function on arguments doesn’t affect actual parameters.
2) Function – Call by reference method – Unlike call by value, in this method, address of actual arguments (or parameters) is passed to the formal parameters, which means any operation performed on formal parameters affects the value of actual parameters.
- The C Standard Library
- C Standard Library Resources
- C Programming Resources
- Selected Reading
Description
The C library function void exit(int status) terminates the calling process immediately. Any open file descriptors belonging to the process are closed and any children of the process are inherited by process 1, init, and the process parent is sent a SIGCHLD signal.
Declaration
Following is the declaration for exit() function.
Parameters
status − This is the status value returned to the parent process.
Return Value
This function does not return any value.
C Programming Void Function
Example
Dev C Void Function On Return Array
The following example shows the usage of exit() function.
Dev C Void Function On Return Value
Let us compile and run the above program that will produce the following result −