Problem-Solving Techniques

	Ask questions.
	Look for things that are familiar.
	Solve by analogy.
	Identify the inputs and outputs.
	Divide and conquer.
	Use building blocks (new or existing).
	Merge solutions.

Problem-Solving Case Study

	Problem: A small company needs an interactive program to figure its weekly payroll. The input data and each employee’s wages should be saved in a secondary storage file, and the total wages for the week should be displayed on the screen so that the payroll clerk can transfer the appropriate amount into the payroll account.
		Data consists of id, hourly pay rate, and hours worked
		Regular wage for 40 hours, time and a half after that
		Store results in a file called payFile
		Use id 0 to indicate end of data since it is not a valid id

Case Study (continued)

	Four obvious steps
		Get the data
		Compute the results
		Output data
		Output total payroll

Main Algorithm

	Open file payFile, Set total payroll to zero
	Get Data
	As long as the employee number is not zero
	Compute Result
	Add employee’s wages to the total payroll
	Output data
	Get data
	Output total payroll

Get Data

	Prompt user for id number
	Read id number
	Prompt user for pay rate
	Read pay rate
	Prompt user for number hours worked
	Read number hours worked

Compute Results

	If hours worked is greater than 40, then
		Wages = 40 * pay rate + (hours – 40) * 1.5 * pay rate
	Otherwise
		Wages = hours * pay rate

Output Data

	Write id number into payFile
	Write pay rate into payFile
	Write hours worked into payFile
	Write wages into payFile

Output Total Payroll

	Write total payroll to the screen

Payroll Program

	//*********************************************
	// Payroll program
	// This program computes each employee’s wages and the
	// total company payroll
	//**********************************************
	#include <iostream>
	#include <fstream>
	using namespace std;
	void CalcPay (float, float, float&);
	const float MAX_HOURS = 40.0; // Maximum normal hours
	const float OVERTIME = 1.5;   // Overtime pay factor

Payroll Program (continued)

	int main
	{
	float payRate; // Employee’s pay rat
	float hours; // Hours worked
	float wages; // Wages earned
	float total; // Total company payroll
	int empNum; // Employee ID number
	ofstream payFile; // Company payroll file
	payFile.open(“payfile.dat”); // Open the output file
	total = 0.0; // Initialize total

Payroll Program (continued)

	cout << “Enter employee number: ”; // Prompt
	cin >> empNum; // Read employee id no.
	while (empNum != 0) // While employee
	{ // number isn’t zero
		cout << “Enter pay rate: ”; // Prompt
		cin >> payRate;         // Read hourly pay rate
		cout << “Enter Hours worked: ”;  // Prompt
		cin >> hours; // Read hours worked
	CalcPay(payRate, hours, wages);  // Compute wages
	total = total + wages; // Add wages to total
	payFile << empNum << payRage // Put results in file
	<< hours << wages;
	cout << “Enter employee number: ”;  //Prompt
	cin >> empNum; // Read ID number
	}
	cout << “Total payroll is ” // Print total payroll
	<< total << endl; //  on screen
	return 0; // Indicate successful
	} //  completion

Payroll Program (continued)

	//*****************************************************
	void CalcPay(/* in */ float payRate, // Employee’s pay rate
	/* in */ float hours, // Hours worked
	/* out */ float& wages) // Wages earned
	// CalcPay computes wages from the employee’s pay rate
	// and the hours worked, taking overtime into account
	{
	if (hours > MAX_HOURS; // Is there overtime?
	wages = (MAX_HOURS * payRate) + // Yes
	(hours – MAX_HOURS) * payRate * OVERTIME;
	else
	wages = hours * payRate; // No
	}

Always Remember and Never Forget

	Computers are dumb; they must be told what to do.
	A computer is a tool to help you solve problems.
	You need to apply the same strategies to solving problems using a computer as you do by hand.