Getting Started

Chapter 4: C Types, Operators, and Expressions

external conditions. For

xample, if the tem ° F, turn the fan on, if it is under 100° F,

d write this as:

Fan(OFF);

r you could use the C conditional operator ?: (

able 3

temp > 150? Fan(ON) : Fan(OFF);

he op rm: expresson1? expression2 : expression3, and follows

ut you’ll see this expression a

hen a sequence of operators such as:

The co er of calculation based on operator precedence (Table
7). But y not be what you intended. Calculate the
value o. D ons quentially as
listed you get:

10 / 2 – 20 * 4

x = 40

Conditional Expressions................................................................................

You will frequently need to make decisions based on
e perature is above 150
turn the fan off. You coul

if( temp > 150)
Fan(ON);
else

O

T ) as below:

T eration has the fo
the rule that if expression1 is true (non-zero value) then use expression2,
otherwise use expression3. This operator seems a little gee-wiz-impress-your-
friends and not as clear as the if-else expression, b
lot, so get used to it.

Precedence and Order of Evaluation.............................................................

W statement has a

x = 50 + 10 / 2 – 20 * 4;

mpiler follows an ord

what the compiler does, ma

f x id you get 40? If you performed the calculati se

x = 50 +

x = 60 / 2 – 20 * 4

x = 30 – 20 * 4

x = 10 * 4