Matakuliah
Tahun
Versi
: D0524 / Algoritma dan Pemrograman Komputer
: 2005
:
Pertemuan 04
Expression
1
Learning Outcomes
Pada akhir pertemuan ini, diharapkan mahasiswa
akan mampu :
• Menghasilkan ekspresi logikal dengan
menggunakan operator perbandingan dan
operator logikal
2
Outline Materi
•
•
•
•
Expression, Operator and Function
Arithmetic Expression
String Expression
Logical Expression
3
Expressions
• An expression tells the computer to manipulate
data.
• The statement tells the computer what to do with
the results of an expression.
• Expressions are composed of values, operators,
and functions.
• Types of expressions:
– Arithmetic expressions
• To perform arithmetic operations.
– String expressions
• To manipulate string data.
– Logical expressions
• To select an appropriate action.
4
Expressions
• Statements
– Perform various tasks
• Evaluate expressions one at a time.
• Carry out tasks specified in expressions.
• Expressions
– Single values or a combination of values, operators, and/or functions
that reduce to a single value.
– Evaluated by calculation or manipulation.
– Result in numeric, string, or Boolean values.
• Operators
– Symbols for a common operations such as addition or multiplication.
– Most operators are binary operators.
• Functions
– Descriptive names that specify a more complex operation than that
performed by an operator.
– Names are always followed by parentheses.
– The value between the parentheses is called the argument.
– The resulting value is called the return value.
5
Expressions
• More Complicated Expressions
– Operators and functions can be composed
into complicated expressions.
– A function’s argument may be complex.
• Ex. X = Math.Sqrt(10 + Math.Sqrt(Y + 29))
• Expressions as a Part of Statements
– An expression is always a part of a statement.
• Ex. Z = Math.Sqrt(X + 2 + Y) + Math.Sqrt(4)
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Arithmatic Expressions
• Arithmetic operators and functions must be written
according to Visual Basic syntax.
• Arithmetic Operators and Operator Precedence
– Arithmetic operations must adhere to the following order:
1. Exponentiations
2. Unary negations
3. Multiplications and Divisions
4. Integer divisions
5. Modulus operations
6. Additions and Subtractions
• Integer Division
– Calculates the number of times one integer goes into another,
discarding the reminder.
– Mod calculates the reminder when one integer is divided by
another.
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String Expressions
•
Manipulate strings using string operators and functions.
– String Operators
• & is the only string operator in Visual Basic
• Joining two string values is called concatenation.
– Functions Used with Strings
• Format()
– Converts a numeric value to a string and formats it.
• Left(), Right(), and Mid()
– Selects specific character(s) in a string.
• StrConv()
– Converts a string into a new string using conversion rules.
• LTrim(), Rtrim(), and Trim()
– Remove leading and trailing spaces.
• Len()
– Determines the number of characters in a string.
• Space()
– Indicates the number of spaces to create.
• InStr()
– Conducts a string search.
• Asc() and Chr()
– Access values in the ANSI table.
• Replace()
– Perform a search and replace routine.
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Logical Expressions
•
•
•
Used to select an action from alternative actions.
Results in a True or False answer to a test.
Also known as Boolean expressions.
– Comparison Operators
•
•
•
•
•
•
<
<=
>
>=
=
<>
– Comparison of Strings
• Strings are ranked alphabetically.
– Logical Operators
• Combine simple logical expressions to create more complex expressions.
• Common operators are Not, And, and Or.
– Logical Functions
• Common ones are IsNumeric() and IIf().
• IsNumeric() is True if the argument is a valid number.
• IIf() chooses between two alternate paths.
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