In this lesson, we will
learn how to use some of the string manipulation function such as
Len, Right,
Left, Mid, Trim, Ltrim, Rtrim, Ucase, Lcase, Instr, Val, Str ,Chr and
Asc.
The Len Function
The length function returns an integer value which is the
length of a phrase or a sentence, including the empty spaces. The format
is
Len
(“Phrase”)
For example,
Len (VisualBasic)
= 11 and Len (welcome to VB tutorial) = 22
The Len function can also return the number of digits or
memory locations of a number that is stored in the computer. For
example,
Private sub
Form_Activate ( )
X=sqr (16)
Y=1234
Z#=10#
Print Len(x),
Len(y), and Len (z)
End Sub
will
produce the output 1, 4 , 8. The reason why the last value is 8 is
because z# is a double precision number and so it is allocated more
memory spaces.
The Right Function
The Right function extracts the right portion of a phrase.
The format is
Right
(“Phrase”, n)
Where n is the starting position from the right of the
phase where the portion of the phrase is going to be extracted. For
example,
Right(“Visual
Basic”, 4) = asic
The Left Function
The Left$ function extract the left portion of a phrase.
The format is
Left(“Phrase”, n)
Where n is the starting position from the left of the
phase where the portion of the phrase is going to be extracted. For
example,
Left
(“Visual Basic”, 4) = Visu
The Ltrim Function
The Ltrim function trims the empty spaces of the left
portion of the phrase. The format is
Ltrim(“Phrase”)
.For example,
Ltrim (“
Visual Basic”, 4)= Visual basic
The Rtrim Function
The Rtrim function trims the empty spaces of the right
portion of the phrase. The format is
Rtrim(“Phrase”)
.For example,
Rtrim
(“Visual Basic ”, 4) = Visual basic
The Trim function
The Ttrim function trims the empty spaces on both side of
the phrase. The format is
Trim(“Phrase”)
.For example,
Trim (“
Visual Basic ”) = Visual basic
The Mid Function
The Mid function extracts a substring from the
original phrase or string. It takes the following format:
Mid(phrase, position, n)
Where position is the starting position of the phrase from
which the extraction process will start and n is the number of
characters to be extracted. For example,
Mid(“Visual
Basic”, 3, 6) = ual Bas
The InStr function
The InStr function looks for a phrase that is
embedded within the original phrase and returns the starting position of
the embedded phrase. The format is
Instr (n,
original phase, embedded phrase)
Where n is the position where the Instr function will
begin to look for the embedded phrase. For example
Instr(1,
“Visual Basic”,” Basic”)=8
The Ucase and the Lcase functions
The Ucase function converts all the characters of a
string to capital letters. On the other hand, the Lcase function
converts all the characters of a string to small letters. For example,
Ucase(“Visual Basic”) =VISUAL BASiC
Lcase(“Visual Basic”) =visual basic
The Str and Val functions
The Str is the function that converts a number to a
string while the Val function converts a string to a number. The
two functions are important when we need to perform mathematical
operations.
The Chr and the Asc functions
The Chr
function returns the string that corresponds to an ASCII code while the
Asc function converts an ASCII character or symbol to the
corresponding ASCII code. ASCII stands for “American Standard Code for
Information Interchange”. Altogether there are 255 ASCII codes and as
many ASCII characters. Some of the characters may not be displayed as
they may represent some actions such as the pressing of a key or produce
a beep sound. The format of the Chr function is
Chr(charcode)
and the
format of the Asc function is
Asc(Character)
The
following are some examples:
Chr(65)=A,
Chr(122)=z, Chr(37)=% , Asc(“B”)=66, Asc(“&”)=38
Source: vbtutor WEB
Source: vbtutor WEB