Page 93 - DCAP202_Fundamentals of Web Programming

Fundamentals of Web Programming

Notes

Task Make distinction between String expression and logical expression.

7.2.1 Conditional Expression

A conditional expression can have one of two values based on a condition. The syntax is (condition)
? val1 : val2 If condition is true, the expression has the value of val1, otherwise it has the value
of val2. You can use a conditional expression anywhere you would use a standard expression.

Example: Status = (age >= 18) ? “adult” : “minor”
This statement assigns the value “adult” to the variable status if age is eighteen or greater.
Otherwise, it assigns the value “minor” to status.

Self Assessment

Fill in the blanks:
11. An ........................... is any valid set of literals, variables, operators, and expressions that
evaluates to a single value.
12. The special keyword null denotes a ...........................
13. A expression can have one of two values based on a ...........................

14. ........................... expression evaluates to a character string
15. Variables that have not been assigned a value are undefined, and cannot be used without
a ........................... error.

7.3 Summary

 An operator is a symbol (it can also be a word) that performs calculations, comparisons or
assignment on one or more values.
 The most common operators are mathematical operators; +, -, /, *.

 Same logic applies to Bitwise operators so they will become like <<=, >>=, >>=, &=, |= and
^=.
 —. a++ increments a and returns the old value of a. ++a increments a and returns the new
value of a.
 Increment operators may be applied before or after a variable.
 There is an operator called conditional operator. This first evaluates an expression for a
true or false value and then execute one of the two given statements depending upon the
result of the evaluation.

 The typeof is a unary operator that is placed before its single operand, which can be of any
type.

 The precedence of operators determines the order they are applied when evaluating an
expression.

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