In this case, the code is testing to see if the hours worked entered by the user is greater than 40, the value in the constant REGULAR_HOURS. If the answer is yes, the code in the brackets just after the test is executed; if not, the code in the brackets just after the 'else' is executed. When you stop to consider it, this is exactly the same way we would use an 'if...else' statement in English. Don't read into this construct something mysterious or complex.

Note further that there is no loop here. Either the code in the first set of brackets is executed OR the code in the second set is executed but not both and NOT over and over. Don't confuse the 'if' and 'while' statements. They have quite different purposes.

The code inside the 'if' statement should be clear from our earlier discussion of the arithmetic operators. The one new part is that the single arithmetic expression:

        overtimeSalary = (hoursWorked - REGULAR_HOURS) *
                                          overtimeRateOfPay;

             overtimeSalary 
                = 
                (hoursWorked 
                - 
                REGULAR_HOURS) 
                                        * 
                                        
                overtimeRateOfPay;

void main()
// Purpose:     to calculate and output the salaries for 10 
//              employees based on rate of pay and hours worked data entered 
//              by a user
// Receives:    NONE
// Returns:     NONE
        
{
        double rateOfPay;
        double overtimeRateOfPay;
        
        double regularSalary;
        double overtimeSalary;
        double fullSalary;                 
        double hoursWorked;  // can be a fraction of an hour

        int count = 0;  // initialize the counter to 0

        while (count < 10)
        {      cout << "Please enter your rate of pay";
                cin >> rateOfPay;
                cout << "Please enter the hours you worked this week";
                cin >> hoursWorked;
                if (hoursWorked > REGULAR_HOURS)
                {      regularSalary = REGULAR_HOURS * rateOfPay;
                        overtimeRateOfPay = rateOfPay * OVERTIME_ADJUSTMENT;
                        overtimeSalary = (hoursWorked - REGULAR_HOURS) * 
                                                  overtimeRateOfPay; 
                        fullSalary = regularSalary + overtimeSalary;
                }
                else
                {      fullSalary       = hoursWorked * rateOfPay;
                }

                cout << "Your salary is: " << fullSalary << endl;
                count++;
        }  

 }

// A program to count the number of employees who worked more than 40 hours
// during the last pay period
// File: ch2prg8.cpp

#include <iostream.h>

const int REGULAR_HOURS = 40;

void main()
// Purpose:     to count the number of employees working overtime
// Receives:    NONE
// Returns:     NONE
        
{        
        double hoursWorked;  // can be a fraction of an hour

        int count = 0;  // initialize the counter to 0
        int numEmployeesWorkingOvertime = 0;

        while (count < 10)
        {      cout << "Please enter the hours you worked this week";
                cin >> hoursWorked;
                if (hoursWorked > REGULAR_HOURS)
                {      numEmployeesWorkingOvertime++;
                }
                count++;
        }  
        cout << "The # of employees working overtime: "
                << numEmployeesWorkingOvertime;

 }

The 'equal' symbol is used in comparisons. It essentially asks the question- is the left side equal to the right side and the answer that comes backis always C++'s equivalent of 'Yes' or 'No' / 'True' or 'False'. You needto be careful to always use "==" within 'if' and 'while' test conditionsor the results you get might surprise you.

Unfortunately, the compiler may give you a warning when you use '=' when you mean '==' but it will let you go ahead. (Compilers have at least two levels of messages - 1) error messages - which are so serious that the compiler cannot translate the code and 2) warning messages which mean - "There might be a problem here that you should look at but I will go ahead and translate your code.") Watch out for these warning messages!

The compiler can make the translation when you use '=' instead of '==' in a test condition because all operators in C++ return a valueand because of the way C++ treats True and False. "Returning a value" isan idea that you have already implicitly worked with. When you write:

the '*' operator 'returns' the value calculated by multiplying 'hoursWorked'by 'rateOfPay'. If '*' did not 'return' a value, there would be nothingto store in 'fullSalary'. All arithmetic operators (such as +, +=, -, -+,*=, /, /+, ++, --) return a value for the same reason.

In C++ not only arithmetic operators but all other types of operators return a value. For instance, the relational operators return a value.But, what value do '<', '>', '==' or the other relational operators return? It turns out that they return the value TRUE or FALSE where FALSE is defined as zero and TRUE is defined as ANY other value - – with 1 being the usual value. In other words, if we have the strange test "3 < 5", the'<' operator will return '1' since 3 is less than 5. But, if we have "3 == 5", the operator '==' returns 0 since 3 does NOT equal five. (Bythe way, note that "3 == 5" and "3 < 5" are not statements of fact asthey would be in mathematics, they are operators that perform a test -Remember our earlier discussion of the difference in the way mathematicsand C++ interpret the '=' symbol.)

The final piece to this puzzle is that the assignment (=) operator returnswhatever value has been assigned. In other words, if we have the line ofcode:

'sum' gets the value 7 and 7 is returned by the '=' operator. Now considerthe line:

The programmer probably meant to write "(sum == 0)" which simply tests to see if 'sum' contains 0. However, by writing "(sum = 0)" the programmer is telling the computer to place 0 in the memory location symbolized bythe variable 'sum' and return that 0. Two problems arise: First, sincethe code always returns 0, the test is always determined to be False (sinceFalse is defined in C++ as 0)! Second, whatever value was in the variable'sum' has been lost, replaced by 0. It is possible but unlikely that thisis what the programmer wanted. The moral of the story - "Be careful touse "==' instead of '=' in equality tests." and "Pay attention to warningmessages." (OK, so there are two morals to this 'story'.)

With this we complete our first look at the basics of C++. In the next chapter we will begin exploring tools we can use to make sure that thecode we write is not only syntactically (grammatically) correct but thatit causes a computer to perform the steps we actually want performed.

Examples of the 'if' Statement