Learn to Program with C_ Learn to Program using the Popular C Programming Language ( PDFDrive )

Chapter 4 ■ Programs with Selection Logic
For example, the pre-processing step changes
if (jobCharge < MinJobCost) jobCharge = MinJobCost;
to
if (jobCharge < 150) jobCharge = 150;
Suppose, for instance, that the minimum job cost changes from 150 to 180. We would just need to
change the value in the #define directive, thus:
#define MinJobCost 180
No other changes would be needed.
In this book, we will use the convention of starting a symbolic constant identifier with an
uppercase letter. Note, however, that C allows you to use any valid identifier.
4.6.2 Example – Symbolic Constants
For a slightly bigger example, consider program P4.5. There, we used two constants—40 and
1.5—denoting the maximum regular hours and the overtime rate factor, respectively. We rewrite
program P4.5 as program P4.7 using the symbolic constants MaxRegularHours (set to 40) and
OvertimeFactor (set to 1.5).
Program P4.7
#include <stdio.h>
#define MaxRegularHours 40
#define OvertimeFactor 1.5
int main() {
double hours, rate, regPay, ovtPay, grossPay;
printf("Hours worked? ");
scanf("%lf", &hours);
printf("Rate of pay? ");
scanf("%lf", &rate);
if (hours <= MaxRegularHours) {
regPay = hours * rate;
ovtPay = 0;
}
else {
regPay = MaxRegularHours * rate;
ovtPay = (hours - MaxRegularHours) * rate * OvertimeFactor;
}
grossPay = regPay + ovtPay;
printf("\nRegular pay: $%3.2f\n", regPay);
printf("Overtime pay: $%3.2f\n", ovtPay);
printf("Gross pay: $%3.2f\n", grossPay);
}
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