Question

Visual Studio Basic

1: Which string function you will be likely using to search for a certain pattern in a string?
Describe your answer.

2: If you are to find the occurrence of 4-letter string “abcd” regardless of its case combinations,
such as “AbCd”, “ABCd” and etc, in a long string, what would you do? Describe your answer.

Answer 1

Strings.StrComp(String, String, CompareMethod) Method

Returns -1, 0, or 1, based on the result of a string comparison.

C#

public static int StrComp (string String1, string String2, Microsoft.VisualBasic.CompareMethod Compare = Microsoft.VisualBasic.CompareMethod.Binary);

Parameters

String1

String

Required. Any valid String expression.

String2

String

Required. Any valid String expression.

Compare

CompareMethod

Optional. Specifies the type of string comparison. If Compare is omitted, the Option Compare setting determines the type of comparison.

Returns

Int32

The StrComp function has the following return values.

TABLE 1

If	StrComp returns
String1 sorts ahead of String2	-1
String1 is equal to String2	0
String1 sorts after String2	1

Exceptions

ArgumentException

Compare value is not valid.

Examples

This example uses the StrComp function to return the results of a string comparison.

VB

' Defines variables. Dim testStr1 As String = "ABCD" Dim testStr2 As String = "abcd" Dim testComp As Integer ' The two strings sort equally. Returns 0. testComp = StrComp(testStr1, testStr2, CompareMethod.Text) ' testStr1 sorts before testStr2. Returns -1. testComp = StrComp(testStr1, testStr2, CompareMethod.Binary) ' testStr2 sorts after testStr1. Returns 1. testComp = StrComp(testStr2, testStr1, CompareMethod.Binary) 

Remarks

The strings are compared by alphanumeric sort values beginning with the first character. For further information on binary comparisons, textual comparisons, and sort order, see Option Compare Statement.

The Compare argument settings are:

TABLE 2

Constant	Description
Binary	Performs a binary comparison, based on a sort order derived from the internal binary representations of the characters.
Text	Performs a text comparison, based on a case-insensitive text sort order determined by your system's LocaleID value.