LEARNINGS OF THE WEEK
BY: Sharra Mae S. Tagaro IV- Rizal
BY: Sharra Mae S. Tagaro IV- Rizal
Conditional Statements
-Are statements that check an expression then may or may not execute a statement or group of statement depending on the result of the condition.
Types of Conditional Statement
1.)The If Statement
2.)The If-Else Statement
3.)The Nested-If Statement
4.)The If-Else-If Ladder
5.)The Switch Statement
6.)The Nested Switch Statement
1.)The If Statement
-Are statements that check an expression then may or may not execute a statement or group of statement depending on the result of the condition.
Types of Conditional Statement
1.)The If Statement
2.)The If-Else Statement
3.)The Nested-If Statement
4.)The If-Else-If Ladder
5.)The Switch Statement
6.)The Nested Switch Statement
1.)The If Statement
l*The general form of the If statement is:
if ( expression)
statement;
-Expression is relational or Boolean expression that evaluates to a TRUE (1) or False (0) value. - Statement may either be a single C statement or a block of C statements.
* The general form of the If statement with block statement is:
*
if ( expression)
{
statement_sequence;
}
2.) The If-Else statement
*The general form of the if-else statement is:
l
*The general form of the if-else statement is:
If (expression)
statement_1;
else
statement_2;
l-Where:
–If and else are reserved words.
–Expression is relational or Boolean expression that evaluates to a TRUE (1) or False (0) value.
Statement_1 and statement_2 may either be a single C statement or a block of C statements.
l*The general form of the if-else statement with block of statement is:
lNote: Only the code associated with the if or the code that is associated with the else
executes, never both.
l*Consider the following situations:
l1. if….. l2. if …… … l3. else –Situations 2. The else in number 5 is paired with the if in number 1. l1. if …. l2. { l3. if …. l4. } l5. else l-Note that there is a pair of braces found in number 2 and number 4. l-This makes the if statement in number 1 the nearest if statement to the else statement in
number 5.
If (expression)
{ statement_sequence;
}
else
{
statement_sequence;
}
l-If an if-else statement, if the expression is TRUE (1), the statement or block of statement after the if statement will be executed; otherwise, the statement or block of statement in the else statement will be executed.
executes, never both.
l
3.)Nested-If statement -One of the most confusing aspects of the if statement in any programming language is nested ifs. A nested if is an if statement that is the object of either an if or else.
3.)Nested-If statement
l-This is sometimes referred to as “an if within an if.”
l-The reason that nested ifs are so confusing is that it can be difficult to know what else associates with what if.
-In C, the else is linked to the closest preceding if that does not already have an else statement associated with it.
–Situations 1. The else at number 3 is paired with the if in number 2 since it is the nearest if statement with the else statement.
l-The pair of braces defined the scope of the if statement in number 1 starting from the { in number 2 and ends with } in number 4.
l-Therefore, the else statement in number 5 cannot paired with the if statement in number 3 because the else statement is outside the scope of the first if statement.
number 5.
4.)The if-else-if Ladder
l-A common programming construct in C is the if-else- if ladder.
l*The general form of the if-else-if ladder statement is:
if ( expression_1)
statement_1;
else if (expression_2)
statement_2;
else if (expression_3;
statement_3;
:
:
else
statement_else;
–If and else are reserve words in C –Statement_1, statement_2 up to statement_else may either be a single C statement or a block
of C statement. l-In an if-else-if ladder statement, the expression are evaluated from the top downward.
l-Where:
–Expression_1, expression_2 up to expression_n in relational or boolean expression that evaluates to a TRUE (1) or False (0) value.
of C statement.
l-As soon as a true condition is found, the statement associated with it is executed and the rest of
lthe ladder will not be executed. If none of the condition is true, the final else is executed.
l-The final else acts as a defaults condition. If all other conditions are false, the last else
statement is performed. l-If the final else is not present, then no action takes place. lNote: The final else is optional, you may include this part if needed in the program or you may
not include if not needed.
5.)The switch statement
6.)The Nested Switch Statement
*The general form of the nested switch statement is:
statement is performed.
not include if not needed.
5.)The switch statement
l-The switch statement is a multiple-branch decision statement.
l*The general form of the switch statement is:
l-In a switch statement, a variable is successively tested against a list or integer or character
constants. l-If a match is found, a statement or block of statement is executed. l-The default part of the switch is executed if no matches are found.
l-According to Herbert Schildt (1992), there are three important things to know about switch
statements:
switch (variable)
{
case constant1:
statement sequence_1;
break;
case constant2:
statement_sequence_2;
break;
:
:
default:
statement_sequence_default;
}
constants.
statements:
–1. The switch differs from if statements in such a way that switch can only test fro equality whereas if can evaluate a relational or logical expression.
–2. No two case constants in the same switch can have identical values. Of course, a switch statement enclosed by an outer switch may have case constant that are the same.
3. If character constants are used in the switch, they are automatically converted to their integer values.
Note: The break statement is used to terminate the statement associated with each case constant. It is a C keyword which means that at the point of execution, you should jump to the end of the switch statement by the symbol }.
3. If character constants are used in the switch, they are automatically converted to their integer values.
Note: The break statement is used to terminate the statement associated with each case constant. It is a C keyword which means that at the point of execution, you should jump to the end of the switch statement by the symbol }.
6.)The Nested Switch Statement
*The general form of the nested switch statement is:
switch (variable)
{
case constant:{
switch (variable)
{
case constant1:
statement sequence_1;
break;
case constant2:
statement_sequence_2;
break;
}
break;
}
case constant2:
statement sequence;
break;
default:
statement sequence;
}
