In this lesson, you learned about Visual C++'s looping capabilities. You saw the following:
Project 6 Listing. Using a for loop to compute interest controlled by the user's input.
1:// Filename: PROJECT6.CPP
2:// Computes interest over a number of periods
3:#include <iostream.h>
4:
5:
6:void main()
7:{
8: int periods; // Number of periods in the loan
9: int count; // Loop control variable
10: float intRate; // Interest rate per period
11: float principal; // Loan amount
12:
13: cout << "Welcome to loan central!" << endl; // Title
14: cout << "------------------------" << endl << endl;
15:
16: cout << "How much was the loan for? ";
17: cin >> principal;
18:
19: cout << endl << "What is the interest rate (i.e., .03 ";
20: cout << "for 3%) per period? ";
21: cin >> intRate;
22:
23: cout << endl << "How many periods are in the loan? ";
24: cin >> periods;
25:
26: for (count = 0; count < periods; count++)
27: { principal *= (1 + intRate); } // Compounds the interest
28:
29: cout.precision(2);
30: cout.setf(ios::showpoint);
31: cout.setf(ios::fixed);
32: cout << endl << "$" << principal << " total amount owed after "
33: << periods << " periods." << endl;
34: return;
35:}
Output
Welcome to loan central! ------------------------ How much was the loan for? 2500.00 What is the interest rate (i.e., .03 for 3%) per period? .11 How many periods are in the loan? 5 $4212.65 total amount owed after 5 periods.
Description
1: A C++ comment that includes the program's filename.
2: A C++ comment that contains the program's description.
3: cout and cin need information in the IOSTREAM.H header file.
4: Place blank lines throughout a program for readability.
5: Place blank lines throughout a program for readability.
6: All functions have names, and the first function in all C++ programs is main().
7: All functions begin with a left brace.
8: Defines an integer variable that will hold the number of periods in the loan.
9: Defines an integer variable that will control the for loop.
10: Defines a floating-point variable that will hold the interest rate.
11: Defines a floating-point variable that will hold the loan principal (the amount borrowed).
12: Extra blank lines make your program more readable.
13: Prints a title.
14: Underlines the title on-screen with hyphens.
15: Extra blank lines make your program more readable.
16: Prompts the user for the amount of the loan (the principal).
17: Gets the principal from the user.
18: Extra blank lines make your program more readable.
19: Prompts for the interest rate. The user is reminded to enter the interest as a decimal.
20: The rest of line 19's cout.
21: Gets the interest rate.
22: Extra blank lines make your program more readable.
23: Prompts for the number of periods in the loan (called the loan term).
24: Gets the term from the user.
25: Extra blank lines make your program more readable.
26: The for loop ensures that the interest calculation computes for the full term entered by the user in line 25.
27: The body of the for loop is only a single statement. The principal increases by the amount of each period's interest rate.
28: Extra blank lines make your program more readable.
29: Ensures that two decimal places print.
30: Prints the decimal point.
31: Guards against scientific notation.
32: Prints the computed loan principal including all accrued interest.
33: Continues the loan balance's printing.
34: Returns to QuickWin control window.
38: main()'s closing brace to terminate the program.
1: You saw another version of this program in Unit 7, but that program didn't have the looping capability that this program does. As a result, Unit 7's program was longer and less flexible!
9: All for loops require a loop control variable.
26: The for loop compounds the loan in one step.