Conditional Statements
These statements serve to perform different set of statements depending on condition value.
If Statement
On the basis of the Condition value,
this statement decides whether the Statement should be executed.
If the Condition is true,
the Statement is executed.
If it is false, the Statement is ignored and the process continues next
after the if statement.
The Statement is either a simple statement or a block of statements:
if (Condition) Statement
Unlike the previous version of the if statement
(in which the Statementis executed only if the Condition is true),
other Statements that should be executed
even if the Condition value is false can be added to the if statement.
Thus, if the Condition is true,
the Statement1 is executed, if it is false,
the Statement2 is executed. See below:
if (Condition) Statement1 else Statement2
The Statement2 can even be another
if statement, and also with an else branch:
if (Condition1) Statement1 else if (Condition2) Statement3 else Statement4
Example 67.23. If statement
integer a = 123; if ( a < 0 ) { a = -a; }
Switch Statement
Sometimes you would have very complicated statement
if you created the statement of more branched out if statement.
In this case, it is much more convenient to use the switch statement.
Now, instead of the Condition as in the if statement
with only two values (true or false), an Expression is evaluated and
its value is compared with the Constants specified in the switch statement.
Only the Constant that equals to the value of the Expression
decides which of the Statements is executed.
If the Expression value is Constant1,
the Statement1 will be executed, etc.
![]() | Important |
|---|---|
Remember that literals must be unique in the |
switch(Expression) { case Constant1 : Statement1 StatementA [break;] case Constant2 : Statement2 StatementB [break;] ... case ConstantN : StatementN StatementW [break;] }
The optional break; statements ensure
that only the statements corresponding to a constant will be executed.
Otherwise, all below them would be executed as well.
In the following case, even if the value of the Expression
does not equal the values of the Constant1,...,ConstantN,
the default statement (StatementN+1) is executed.
switch (Expression) { case Constant1 : Statement1 StatementA [break;] case Constant2 : Statement2 StatementB [break;] ... case ConstantN : StatementN StatementW [break;] default : StatementN+1 StatementZ }
Example 67.24. Switch statement
integer ok = 0; switch ( response ) { case "yes": case "ok": a = 1; break; case "no": a = 0; break; default: a = -1; }
![[Important]](../figures/important.png)