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Quoting Strings
Along with strings； Visual Basic has the Char type。 A Char can be described as a single letter of a
sentence。 However； it would be more accurate to say that it is a single character。 You can assign
a string to a Char type； as long as Option Strict is Off （which it is by default）。 For example； suppose
you wrote the following code to assign a string to the variable val。
' The Option Strict declaration must e right at the top of your code
Option Strict Off
。 。 。
Dim val As Char
val = 〃hello〃
The example piles； but you will not get what you want。 Because Option Strict is Off；
the string is converted to a character。 In this conversion； data is lost—specifically； the characters
ello are lost。 The value stored in the variable val is the single letter h。
If Option Strict were On； the example would not pile。 When Option Strict is On； the
piler does not do conversions where data might be lost。 If you have code that does attempt
a conversion； an error will be flagged by the piler。
If you really wanted to store the single letter h in the variable val； you would need to explicitly
define the character to be assigned to the variable； as follows：
Option Strict On
。 。 。
Dim val As Char
val = 〃h〃c
To define a single…character string； you enclose that character in double quotation marks；
followed by a lowercase c to indicate that the single…character string is a character。
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66 CH AP T E R 3 ■ L E A R N IN G AB OU T ST R I N G M A N I P U L AT IO N S
VISUAL BASIC STRICT AND EXPLICIT
Programming languages have two distinct flavors： static typed and dynamic typed。 Do not get these two terms
confused with the terms strongly typed and weakly typed。 Those two sets of terms are orthogonal to each
other。 A language can be dynamic typed and strongly typed at the same time。 For example； the following code
is strongly and dynamic typed。
Dim a = 10
The type is dynamic because I have not declared the variable to be of any type。 It is strongly typed because
when a is assigned to a value of 10； it is defined to be an Integer。 A strongly and dynamic typed language
means that variables can be any type； but once they are assigned； their type cannot be changed。 Thus； you
cannot convert an integer to a string or a string to an integer without some type of failure。
The following code is weakly and static typed。
Dim val As Char = 〃hello〃
Here； I explicitly say that val is a Char； and I’ve assigned to it a string。 However； because of weak
typing； a strong…armed conversion of the string to a Char is made。 Think of it as fitting a square peg into a
round hole。 If the square peg has a diagonal length less than the diameter of the hole； the process works
without much effort。 But if the square peg’s length is the same as the diameter of the hole； you will need to
use brute force。
Visual Basic allows you to write all types of code； and the flags Option Strict and Option Explicit
relate to what kind of code you want。 When you set Option Strict to On； you are saying that you don’t want
to support weakly typed code。 The flag has no effect on dynamic typing。 The Option Explicit flag does not
affect weakly typed code； but it partially affects dynamic typed code。 Consider the following code that piles
when Option Explicit is set to Off。
a = 10
The code is an assignment； but you don’t know if the variable is declared in the file； in the class； or local
to the method。 The variable could be defined out of the blue and then used。 Dynamic typing allows this； but
again； after the variable has been assigned； it stays the same type。 When you set Option Explicit to On；
you are making an explicit declaration of the variable a requirement。
With all of these options； you are left wondering which bination of flags you want。 The answer is that
it depends on what style of programmer you are。 If you want a traditional language （like C#； Java； C＋＋； and
so on）； then you should have both flags set to On。 If you want a more dynamic programming language （like
Python； Ruby； PHP； and so on）； then you should have both flags set to Off。 Unless you have experience in the
dynamic programming environment and know what side effects may occur； you should start off taking the
traditional language approach。 For that reason； the code in this book is written with both flags set to On。
You can define the Option Strict and Option Explicit flags in the source code； as shown in the
examples in the previous “Quoting Strings” section； or you can set them in the pile settings of the individual
project settings or for the whole of Visual Basic Express。 To set them for a project； right…click the project
name and select Properties pile。 The two settings are in the drop…down boxes at the top of the page。
To set the options for all projects； select Tools Options； and then select Projects and Solutions VB Defaults。
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CH AP T E R 3 ■ L E AR N IN G AB O U T ST R I N G M A N I PU L A TI O N S 67
Character Mapping
A single character takes 16 bits of spa