A function is a block of code that executes certain commands when it is called. Functions are important for reusing code and making programs more efficient. Each program has at least one function main$().$ User$-$defined functions are functions that we create to perform tasks. They include the following three parts:

Prototype $$ declares the function telling the compiler to expect a user$-$defined function

Call $$ calls the function definition to complete the specified commands

Definition $$ stores the executable commands

Anatomy of a C function

Things to know about functions:

Parentheses after a named item specify that command as a function $($main$(),$ printf$(),$ scanf$(),$ etc.$).$

After a function definition has been completed, the program returns to the next command directly after the function call.

We can pass parameters or variable values into a function definition to be manipulated, computed, or changed.

We can also return values back to the function call so that these values are available in the scope of another function.

A variable is only available in the scope of its function definition.

For this exercise, you will design a program that prompts the user to enter two numbers. You need to create a function to display a message and prompt the user. You then will add the two numbers together displaying the result on the output screen.