CS201-09 - Introduction to Programming Lecture 9...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Introduction to Programming Lecture 9 Programming Toolkit Decisions Loops Sequences Laboratory Stool Constructing a laboratory Stool Constructing a laboratory Stool Task: Making a stool – Subtask: Make a seat Make legs for the stool Assemble them What we will study today … What are functions? How are they defined ? How are they declared ? What values are passed to functions ? What values do functions return ? Function Function name { Body of the function } Function Two types of functions: 1. Functions that return a value 2. Functions that do not return a value Function return­value­type function­name( argument­list ) { declarations and statements } Declaration of Function return­value­type function­name( argument­­type­list) ; main ( ) { } : Example int function­name ( int , int , double ) ; void main ( ) { …. } Definition of Function int function­name ( int i , double j ) { … } Return Type of Function Declaration int square ( int ) ; Definition int square ( int i ) { return ( i * i ) ; } Function Call int x ; x = square ( i ) ; Example: Function to calculate integer power ( Xn ) double raiseToPow ( double x , int power ) { double result ; int i ; result = 1.0 ; for ( i = 1 ; i <= power ; i ++ ) // braces first { result * = x ; // result = result *x } return ( result ) ; } Code to Call the raisetopow Function include < iostream.h > void main ( ) { double x ; int i ; cout << “ Please enter the number “ ; cin >> x ; cout << “ Please enter the integer power that you want this number raised to “ ; cin >> i ; cout << x << “ raise to power “ << i << “is equal to “ << raiseToPow ( x , i ) ; } Call By Value Calling function Called function Area of the Ring Inner Circle Outer Circle Area of Outer Circle ____ Area of Inner Circle = Area of the Ring Example: Function to calculate the area of a circle double circleArea ( double radius ) { return ( 3.1415926 * radius * radius ) ; } Calculating ringArea without using Function main ( ) { : ringArea = ( 3.1415926 * rad1 * rad1 ) – ( 3.1415926 * rad2 * rad2 ) ; } Exercises 1. Modify the raise to power function so that it can handle negative power of x, zero and positive power of x. For the area of ring function put in error checking mechanism. 1. In today’s lecture We used functions for breaking complex problems into smaller pieces, which is a top­down structured approach. Each function should be a small module, self contained and it should solve a well defined problem. Variable names and function names should be self explanatory. Always comment your code ...
View Full Document

This note was uploaded on 01/12/2010 for the course CS CS 201 taught by Professor Dr.naveedmalik during the Spring '09 term at Virtual University of Pakistan.

Ask a homework question - tutors are online