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For for Control Structures

Fuel Warning

//Illustrates the importance of using braces in if-else statements.
#include <iostream>
using namespace std;
int main( )
{
    double fuel_gauge_reading;

    cout << "Enter fuel gauge reading: ";
    cin >> fuel_gauge_reading;

    cout << "First with braces:\n";
    if (fuel_gauge_reading < 0.75)
    {
        if (fuel_gauge_reading < 0.25)
            cout << "Fuel very low. Caution!\n";
    }
    else
    {
        cout << "Fuel over 3/4. Dont stop now!\n";
    }

    cout << "Now without braces:\n";
    if (fuel_gauge_reading < 0.75)
        if (fuel_gauge_reading < 0.25)
            cout << "Fuel very low. Caution!\n";
    else
        cout << "Fuel over 3/4. Don't stop now!\n";

    return 0;
}
 

Multiway if-else Statement - Program to compute state income tax.

//DISPLAY 3.5 Multiway if-else Statement
//Program to compute state income tax.
#include <iostream>
using namespace std;


//This program outputs the amount of state income tax due computed
//as follows: no tax on income up to $15,000; 5% on income between 
//$15,001 and $25,000; 10% on income over $25,000.


int main( )
{
    int net_income;
    double tax_bill;
    double five_percent_tax, ten_percent_tax;


    cout << "Enter net income (rounded to whole dollars) $";
    cin >> net_income;

 if (net_income <= 15000)
        tax_bill = 0;
    else if ((net_income > 15000) && (net_income <= 25000))
        //5% of amount over $15,000
        taxc_bill = (0.05*(net_income - 15000));
    else //net_income > $25,000
    {
        //five_percent_tax = 5% of income from $15,000 to $25,000.
        five_percent_tax = 0.05*10000;
        //ten_percent_tax = 10% of income over $25,000.
        ten_percent_tax = 0.10*(net_income - 25000);
        tax_bill = (five_percent_tax + ten_percent_tax);
    }

    cout.setf(ios::fixed);
    cout.setf(ios::showpoint);
    cout.precision(2);
    cout << "Net income = $" << net_income << endl
         << "Tax bill = $" << tax_bill << endl;

    return 0;
}
 

A switch Statement

DISPLAY 3.6 A switch Statement
//Program to illustrate the switch statement.
#include <iostream>
using namespace std;

int main( )
{
    char grade;

    cout << "Enter your midterm grade and press Return: ";
    cin >> grade;

    switch (grade)
    {
        case 'A':
            cout << "Excellent. "
                 << "You need not take the final.\n";
            break;
        case 'B':
            cout << "Very good. ";
            grade = 'A';
            cout << "Your midterm grade is now "
                 << grade << endl;
            break;
        case 'C':
            cout << "Passing.\n";
            break;
        case 'D':
        case 'F':
            cout << "Not good. "
                 << "Go study.\n";
            break;
        default:
            cout << "That is not a possible grade.\n";
    }

    cout << "End of program.\n";
    return 0;
}
 

A Menu

//DISPLAY 3.7 A Menu 
//Program to give out homework assignment information.
#include <iostream>
using namespace std;

 
int main( )
{
    int choice;

    do
    {
        cout << endl
             << "Choose 1 to see the next homework assignment.\n"
             << "Choose 2 for your grade on the last assignment.\n"
             << "Choose 3 for assignment hints.\n"
             << "Choose 4 to exit this program.\n"
             << "Enter your choice and press Return: ";
        cin >> choice;
 
        switch (choice)
        {
            case 1:
               //code to display the next assignment on screen would go here.
                break;
            case 2:
               //code to ask for a student number and give the corresponding 
               //grade would go here.
                break;
            case 3:
               //code to display a hint for the current assignment would go 
               //here.
                break;
            case 4:
                cout << "End of Program.\n";
                break;
            default:
                  cout << "Not a valid choice.\n"
                     << "Choose again.\n";
        }
    }while (choice != 4);

    return 0;
}

 

Block with a Local Variable

//DISPLAY 3.8 Block with a Local Variable
//Program to compute bill for either a wholesale or a retail purchase.
#include <iostream>
using namespace std;
const double TAX_RATE = 0.05; //5% sales tax.


int main( )
{
    char sale_type;
    int number;
    double price, total;

    cout << "Enter price $";
    cin >> price;
    cout << "Enter number purchased: ";
    cin >> number;
    cout << "Type W if this is a wholesale purchase.\n"
         << "Type R if this is a retail purchase.\n"
         << "Then press Return.\n";
    cin >> sale_type;

    if ((sale_type = = 'W') || (sale_type = = 'w'))
    {
        total = price * number;
    }
    else if ((sale_type = = 'R') || (sale_type = = 'r'))
    {
        double subtotal;
        subtotal = price * number;
        total = subtotal + subtotal * TAX_RATE;
    }
    else
    {
        cout << "Error in input.\n";
    }
    cout.setf(ios::fixed);
    cout.setf(ios::showpoint);
    cout.precision(2);
    cout << number << " items at $" << price << endl;
    cout << "Total Bill = $" << total;
    if ((sale_type = = 'R') || (sale_type = = 'r'))
        cout << " including sales tax.\n";

    return 0;
}

 

The Increment Operator as an Expression

//DISPLAY 3.10 The Increment Operator as an Expression
//Calorie-counting program.
#include <iostream>
using namespace std;

int main( )
{
    int number_of_items, count,
        calories_for_item, total_calories;

    cout << "How many items did you eat today? ";
    cin >> number_of_items;

    total_calories = 0;
    count = 1;
    cout << "Enter the number of calories in each of the\n"
         << number_of_items << " items eaten:\n";

    while (count++ <= number_of_items) 
    {
        cin >> calories_for_item;
        total_calories = total_calories
                         + calories_for_item;
    }

    cout << "Total calories eaten today = " 
         << total_calories << endl;
    return 0;
}

 

A break Statement in a Loop

//DISPLAY 3.14 A break Statement in a Loop
//Sums a list of ten negative numbers.
#include <iostream>
using namespace std;

int main( )
{
    int number, sum = 0, count = 0;
    cout << "Enter 10 negative numbers:\n";

    while (++count <= 10) 
    {
        cin >> number;

        if (number >= 0)
        {
            cout << "ERROR: positive number"
                 << " or zero was entered as the\n"
                 << count << "th number! Input ends "
                 << "with the " << count << "th number.\n"
                 << count << "th number was not added in.\n";
            break;
        }

        sum = sum + number;
    }

    cout << sum << " is the sum of the first " 
         << (count - 1) << " numbers.\n";

    return 0;
}
 

Explicitly Nested Loops

//DISPLAY 3.15 Explicitly Nested Loops
//Determines the total number of green-necked vulture eggs
//counted by all conservationists in the conservation district.
#include <iostream>
using namespace std;

void instructions ();

int main()
{
cout << "This program tallies conservationist reports\n"
         << "on the green-necked vulture.\n"
         << "Each conservationist's report consists of\n"
         << "a list of numbers. Each number is the count of\n"
         << "the eggs observed in oneî 
         << "green-necked vulture nest.\n"
         << "This program then tallies 
         << "the total number of eggs.\n";

    int number_of_reports;
    cout << "How many conservationist reports are there? ";
    cin >> number_of_reports;

    int grand_total = 0, subtotal, count;
    for (count = 1; count <= number_of_reports; count++)
    {
        cout << endl << "Enter the report of "
             << "conservationist number " << count << endl;
        cout << "Enter the number of eggs in each nest.\n"
             << "Place a negative integer at the end of your list.\nî;î
        subtotal = 0;
       int next;
        cin >> next;
        while (next >=0)
        {
            subtotal = subtotal + next;
            cin >> next;
        }
        cout << "Total egg count for conservationist "
             << " number " << count << " is " 
             << subtotal << endl;
        grand_total = grand_total + subtotal;
    }
    cout << endl << "Total egg count for all reports = "
         << grand_total << endl;

    return 0;
}
 

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Topic revision: r2 - 2017-09-20 - JimSkon
 
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