Function Parameters

A function can be provided input in the form of zero or more variables called parameters. Parameters are created when the function is called, and they are assigned the values provided as arguments. An example of a function with one parameter is: 
int parFunction(char parameter1)
{
    return parameter1;
}
parFunction() returns an int value and takes a char as a parameter. The only statement contained within the function's implementation block returns the input parameter, which is interpreted as an int. When the function is called within another function, for example within main(), an argument has to be passed to it, which will be assigned to parameter1. parameter1 is created when the function is entered and destroyed when the function is exited. For example, the call: 
parFunction('t');
will call the function, assigning 't' to parameter1 and finally returning 't''s ASCII code. Functions can return any type but arrays. Further, functions can contain local variables: i.e. variables declared within the function's body that are unknown outside the function and are deleted (go out of scope) once the function is exited (just like parameters). anotherFunction() contains a local variable: 
void anotherFunction()  // prints alphabet
{
     char localVariable = 'a';
     while(localVariable <='z')
     {
           cout << localVariable << " ";
           localVariable++;
     }
}
The function above contains one local variable, created within the function and destroyed when the function returns. Also, the function does not return any value. For such a reason its return type is void.

Example


#include <iostream>
using namespace std;

int parFunction(char parameter1)
{
    return parameter1;
}

void anotherFunction()  // prints alphabet
{
     char localVariable = 'a';
     while(localVariable <='z')
     {
           cout << localVariable << " ";
           localVariable++;
     }
}

int main()
{
    cout << parFunction('e') << endl;
anotherFunction();
}

Output

101
a b c d e f g h i j k l m n o p q r s t u v w x y z