Lesson 13: String Manipulation Functions.

 

String Manipulation Functions

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.

13.1 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 syntax 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,
X=sqr (16)
Y=1234
Z#=10#
Then Len(x)=1, Len(y)=4, and Len (z)=8
The reason why Len(z)=8 is because z# is a double precision number and so it is allocated more memory spaces.

13.2 The Right Function

The Right function extracts the right portion of a phrase. The syntax is
Right (“Phrase”, n)
Where n is the starting position from the right of the phrase where the portion of the phrase is going to be extracted.  For example,
 Right(“Visual Basic”, 4) = asic

13.3 The Left Function

The Left$ function extract the left portion of a phrase. The syntax 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

12.4 The Ltrim Function

The Ltrim function trims the empty spaces of the left portion of the phrase. The syntax is
Ltrim(“Phrase”)
.For example,
 Ltrim (“  Visual Basic”, 4)= Visual basic

13.5 The Rtrim Function

The Rtrim function trims the empty spaces of the right portion of the phrase. The syntax is
Rtrim(“Phrase”)
.For example,
Rtrim (“Visual Basic      ”, 4) = Visual basic

13.6 The Trim function

The Trim function trims the empty spaces on both side of the phrase. The syntax is
Trim(“Phrase”)
.For example,
Trim (“   Visual Basic      ”) = Visual basic

13.7 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

13.8 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 syntax 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

13.9 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

13.10 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.

13.11 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 syntax of the Chr function is
Chr(charcode)
and the syntax 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

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