Chapter 05 (Part II) Control Statements: Part II

Objectives In part II you will learn: To get familiar with the use of for statements. To use other data type and C++ libraries. To use the do…while repetition statements.

Calculating Amount on Deposit C++ treats floating-point values as type double

Declare Floating-Point Variable Use float or double to declare a floating- point variable. –float type: single precision –double type: single precision –Note: Floating-point values are approximate, so controlling counting loops with floating-point variables can result in imprecise counter values and inaccurate tests for termination.

Calculating Amount on Deposit

Formatting Numeric Output Stream manipulator std:: setw –Setting field width –Must include iomanip #include –Right justified by default Stream manipulator std:: left to left-justify Stream manipulator std:: right to right-justify –Applied only to the next output value

Formatting Numeric Output Example: cout << “Age: ” << left() << setw(3) << age << “ years old” << endl; cout << “Age: ” << right() << setw(3) << age << “ years old” << endl; cout << “Age: ” << setw(3) << age << “ years old” << endl;

Formatting Numeric Output Stream manipulators fixed and setprecision –Sticky settings Remain the next stream manipulator in effect until they are changed. Example cout << fixed << setprecision(2); –cout will not actually display anything but change the output settings. –‘fixed’ will not work on setw().

Calculating Amount on Deposit

5.4 Examples Using the for Statement Standard library function std::pow –Calculates an exponent –pow( x, y ) Calculates the value of x y The computation result is a value with double type. –Example: double x = 4, y = 2.3; double result = std::pow(x, y); –Requires header file

Common Programming Error Forgetting to include the appropriate header file when using standard library functions is a compilation error. Example: #include int main() { double x = 4, y = 2.3; double result = std::pow(x, y); cout << setw(10) << result; return 0; }

C++ treats floating-point values as type double setw stream manipulator will set a field width standard library function pow (in header file ) Specify that the next value output should appear in a field width of 21

Calculate amount within for statement Use the setw stream manipulator to set field width Principal*(1+rate) year

5.5 do … while Repetition Statement do…while statement –Similar to while statement –Testing condition after performing the body Loop body always executes at least once An semicolon must be added right after a do…while statement. –Example: do { body } while (condition) ; Executes at least once.

Good Programming Practice Always including braces in a do...while statement helps eliminate ambiguity between the while statement and the do...while statement containing one statement. Example: int option; do { cin >> option; } while (option != -1);

Declare and initialize control variable counter do…while loop displays counter ’s value before testing for counter ’s final value

Flowchart diagram for the do...while repetition statement