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

Chapter 4 ■ Programs with Selection Logic
Program P4.1
//print job charge based on hours worked and cost of parts
#include <stdio.h>
int main() {
double hours, parts, jobCharge;
printf("Hours worked? ");
scanf("%lf", &hours);
printf("Cost of parts? ");
scanf("%lf", &parts);
jobCharge = hours * 100 + parts;
if (jobCharge < 150) jobCharge = 150;
printf("\nCharge for the job: $%3.2f\n", jobCharge);
}
For this program, we choose to use three variables—hours, parts and jobCharge, all of type
double since we may need to enter floating-point values for hours worked and cost of parts.
It is very important that you make an extra effort to understand the if statement since it is
one of the most important statements in programming. It is the if statement that can make a
program appear to think.
The condition
charge is less than 150
of the pseudocode algorithm is expressed in our program as
jobCharge < 150
When the program is executed, the job charge is calculated in the normal way (hours * 100
+ parts). The if statement then tests if this value, jobCharge, is less than 150; if it is, then
jobCharge is set to 150. If it is not less than 150, jobCharge remains as it is. The statement
if (jobCharge < 150) jobCharge = 150;
is a simple example of the if construct. Observe that the word then is not used in C. In general,
the construct takes the following form in C:
if (<condition>) <statement>
The word if and the brackets around <condition> are required by C. You must supply
<condition> and <statement> where <condition> is a Boolean expression and <statement>
can be either a one-line statement or a block—one or more statements enclosed by { and }.
If <condition> is true, <statement> is executed; if <condition> is false, <statement> is not
executed. In either case, the program continues with the statement, if any, after <statement>.
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