Case statements in C++ program

Case statements in C++ program

Hi Jeffrey,

The case statements or the so-called switch-case statement is a good alternative to cascading if-else statements.

The syntax for the switch-case statement is as follows:

switch(<expression>)

{

case <label-1>: <statement-1>;

[break;] [optional]

case<label-2>: <statement-2>;

[break;] [optional]

case<label-3>: <statement-3>;

[break;] [optional]

case<label-n>: <statement-n>;

[default: <statement-d>;] [optional]

[break;]

}

• The expression may be an integer or character literal or as the name suggests, an expression that evaluates to an integer or a character value.
• The use of float and double data type values will result into an error.
• The <expression> is evaluated and the value compared is within each of the case labels. The case labels must have the same type as the <expression> and they must be unique.
• If the value of the <expression> matches with the case label, the statement(s) the follow will be executed until it reaches the [break]; statement (if present).
• If none of the case labels matched, the statement(s) in the <default> label is executed (if one exists).
• Without the break statement, the statements in following case labels are executed up to the last label.
• Statements associated with a case label can be a single or a sequence of statements.
• Curly brackets can also be added in each case label to make it more readable.

Disadvantages:

• Declarations after the case label without the {} is ignored by the compiler. The switch statement transfers control directly to an executable statement within the body, bypassing the lines that contain initializations.
• Can cause waterfall effect if you forgot to add break before end the case label block (if you intend to).

Advantages:

• A switch statement CAN SOMETIMES be more efficient than an if / else statement, because it is easy for a compiler to generate jump tables from switch statements. It is possible to do the same thing for if / else statements, given appropriate constraints, but that is much more difficult.
• With a large number of strings, there is a significant performance advantage to using a switch statement, because the compiler will use a hash table to implement the jump.