Page 20 - Programming Microcontrollers in C

Some Simple Programs 5

notifies the compiler to generate code that will cause the integer stored
in location a to be multiplied by the integer in b and the result of that
product to be multiplied by the integer found in c. Usually, the name
a, b, or c is used to designate the content of the memory location
assigned to the label name. This integer result will be stored in the
location identified by d.
The print statement
printf(“a * b * c = %d\n”, d);

is similar to the same statement in the first example. In this case,
however, the data string
“a * b * c = %d\n”

contains a printer command character %d. This character notifies the
printf function that it is to take the first argument following the
data string, convert it to a decimal value, and print it out to the screen.
The result of this line of code will be

a * b * c = 100
printed on the screen.
The line of code

d=a*b+c;
demonstrates another characteristic of the language. Each operator
is assigned a precedence that determines the order in which an ex­
pression is evaluated. The parenthesis operators are of the highest
precedence. The precedence of the * operator is higher than that of
the + operator, so this expression will be evaluated as

d=(a*b)+c;
In other words, the product indicated by * will be executed prior
to the addition indicated by the +. The expression that follows later
in the code

d=a+b*c;
will be evaluated as

d=a+(b*c);
causing the result of the third calculation to differ from that of the
second.