Function: Use Defined C + + Function: Function Prototype, Arguments to a Function, Return Type of a Function, Global and Local variables

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Diagram shows types of functions

Diagram Shows Types of Functions

User Defined C++ Function

Image of user defined C++ function

Image of User Defined C++ Function

  • A C++ function is a grouping of program statements in a single unit.

  • The main () is an essential function in all C ++ programs. If there is a single function in a program, it should be named main ().

  • The main () function is the starting point for the execution of a program. The definition of main () would look like as follows:

main ()

{

// main program statements

}

  • In C ++, the main () returns a value of type int to the operating system.

  • The function that has a return value should use the return statement for termination. The main () function, therefore, is defined as follows:

int main ()

{

____

____

____

return (0).

}

Since the return type of function is int by default, the keyword int in main () header is optional.

Consider the program given below:

#include<iostream.h>

void main ()

{

cout < < “Computer Science \n”.

}

It prints computer science on the screen. We can also write the above program in the following way:

# include < iostream.h>

void message ().

void main ()

{

message ().

}

void message ()

{

cout << “Computer Science\n”.

}

The above program also prints computer science, but it uses a function message for printing. In addition to functions main () and message (), the program has an extra line after # include preprocessor directive. The line is void message (). This is known as function prototype.

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