Teach Yourself Borland C++ in 14 Days - portal

52 Day 2
SYNTAX
amountOverSpeedLimit is equal to 10, a value of 20 is assigned to fine, and so on. In each of
the first three cases you see a break statement. The break statement is used to jump out of
the switch block—it means that a case matching the expression has been found, and the rest
of the switch statement can be ignored. Finally, you see the default statement. The code
block following the default statement will be executed if no matching cases are found.
Notice that cases 20 and 25 have no statements following them. If the expression
amountOverSpeedLimit evaluates to 20 or 25, those cases fall through and the next code block
encountered will be executed. In this situation, the values 20, 25, or 30 will all result in the
same code being executed.
WARNING
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Don’t forget your break statements! Without break statements the
switch will continue on even after finding a match and may execute
code you didn’t intend to be executed. Sometimes that is how you want
your switch to perform, but most of the time it is not.
Inclusion of the default statement is not mandatory. You could write a switch without a
default statement:
switch (x) {
case 10 : DoSomething(); break;
case 20 : DoAnotherThing(); break;
case 30 : TakeABreak();
}
Note that there is no break statement following the last case statement. Because this is the
last line of the switch, there is no point in including the break statement for this line.
As I said earlier, you might want to use a switch if you find that you have several if statements
back-to-back. The switch is a bit clearer to others reading your program.
The switch statement:
switch (expr) {
case value_1:
statements_1;
break;
case value_2:
statements_2;
break;
.
.
.
case value_n:
statements_n;
break;