Today we’re gonna talk about Selections in Algorithms & Programmings
Selection Definition
in an algorithm implementation, an instruction or block of instructions may be executed (or not) with certain predetermined condition
Syntax:
–if
–if-else
–switch-case
IF
Syntax :
if (boolean expression) statement;
or
if (boolean expression) {
statement1;
statement2;
……
}
If boolean expression resulting in True, then a statement or some statements will be executed.
Selection: IF-ELSE
Syntax :
if (boolean expression) statement1;
else statement2;
or
if (boolean expression){
statement1;
statement2;
……
}
else {
statement3;
statement4;
…
}
If boolean expression resulting in TRUE, then statement1 or block statement1 will be executed, if FALSE then statement2 or block statement2 be executed.
NESTED-IF
- Nested selection occurs when the word IF appears more than once within IF statement.
Syntax :
if (boolean expression) statement1;
if (boolean expression) statement2;
if (boolean expression) statement3;
or
if (boolean expression) statement1;
else
if (boolean expression) statement2;
else
if (boolean expression) statement3;
SWITCH-CASE
Switch-Case Operation
This statement is used in exchange of IF-ELSE, when if-else nested number of level is enormous and difficult to read
Syntax:
switch (expression) {
case constant1 : statements1; break;
.
.
case constant2 : statements2; break;
default : statements;
}
?: Operator
The operator ? : is similar to the IF statement, but it returns a value
Syntax:
condition ? then-expression : else-expression
Using this operator, you can rewrite
if(a > b)
max_value = a;
else
max_value = b;
as
max_value = (a > b) ? a : b;