programming-for-dummies

174
Using Boolean Operators
The computer examines the first character of each string. If they’re equal, it
continues with the second character, a third, and so on.
In the preceding example, the computer sees that the numbers 97 (which
represent the character a) are equal, so it checks the second character. The
number 65 (A) isn’t greater than the number 97 (a), so this comparison
returns a False value.
What happens if you compare unequal strings, such as
“aA” > “a”
The computer compares each character as numbers as follows:
97 65 > 97
The first numbers of each string (97) are equal, so the computer checks the
second number. Because the second string (a) doesn’t have a second character,
its value is 0. Because 65 > 0, the preceding comparison returns a
True value.
Now look at this comparison:
“Aa” > “a”
The computer translates these characters into their equivalent numbers, as
follows:
65 97 > 97
Comparing the first numbers (characters), the computer sees that 65 > 97, so
this comparison returns a False value. Notice that as soon as the computer
can decide whether one character is greater than another, it doesn’t bother
checking the second character in the first string.
Using Boolean Operators
Comparison operators always return a True or False value, which are
Boolean values. Just as you can manipulate numbers (addition, subtraction,
and so on) and strings (trimming or searching for characters), so can you
also manipulate Boolean values.
When you manipulate a Boolean value, you get another Boolean value.
Because there are only two Boolean values (True or False), every Boolean
operator returns a value of either True or False.