Chapter14:StringManipulation

Section14.1:Replacingastringwithinastring

UsingtheSystem.String.Replacemethod,youcanreplacepartofastringwithanotherstring.

strings=”HelloWorld”;

s=s.Replace(“World”,”Universe”);//s=”HelloUniverse”

Alltheoccurrencesofthesearchstringarereplaced:

strings=”HelloWorld”;

s=s.Replace(“l”,”L”);//s=”HeLLoWorLD”

String.Replacecanalsobeusedtoremovepartofastring,byspecifyinganemptystringasthereplacementvalue:

strings=”HelloWorld”;

s=s.Replace(“ell”,String.Empty);//s=”HoWorld”

Section14.2:Findingastringwithinastring

UsingtheSystem.String.Containsyoucanfindoutifaparticularstringexistswithinastring.Themethodreturns aboolean,trueifthestringexistselsefalse.

strings=”HelloWorld”;

boolstringExists=s.Contains(“ello”);                         //stringExists=trueasthestringcontainsthesubstring

UsingtheSystem.String.IndexOfmethod,youcanlocatethestartingpositionofasubstringwithinanexisting string.

Notethereturnedpositioniszero-based,avalueof-1isreturnedifthesubstringisnotfound.

strings=”HelloWorld”;

intlocation=s.IndexOf(“ello”);//location=1

Tofindthefirstlocationfromtheendofastring,usetheSystem.String.LastIndexOfmethod:

strings=”HelloWorld”;

intlocation=s.LastIndexOf(“l”);//location=9

Section14.3:Removing(Trimming)white-spacefromastring

TheSystem.String.Trimmethodcanbeusedtoremoveallleadingandtrailingwhite-spacecharactersfroma string:

strings=” Stringwithspacesatbothends

s=s.Trim();//s=”Stringwithspacesatbothends”

Inaddition:

Toremovewhite-spaceonlyfromthebeginningofastringuse:System.String.TrimStart

• Toremovewhite-spaceonlyfromtheendofastringuse:System.String.TrimEnd

Substringtoextractpartofastring.

TheSystem.String.Substringmethodcanbeusedtoextractaportionofthestring.

strings=”Aportionofwordthatisretained”;

s=str.Substring(26);            //s=”retained”

s1=s.Substring(0,5);                //s=”Apor”

Section14.4:Splittingastringusingadelimiter

Use the System.String.Splitmethod to return a string array that contains substrings of the original string, split basedonaspecifieddelimiter:

stringsentence=”OneTwoThreeFour”;

string[]stringArray=sentence.Split(”);

foreach(stringwordinstringArray)

{

Console.WriteLine(word);

}

Output:

One

Two

Three

Four

Section14.5:Concatenateanarrayofstringsintoasingle string

TheSystem.String.Joinmethodallowstoconcatenateallelementsinastringarray,usingaspecifiedseparator between each element:

string[]words={“One”,”Two”,”Three”,”Four”};

stringsingleString=String.Join(“,”,words);//singleString=”One,Two,Three,Four”

Section14.6:StringConcatenation

StringConcatenationcanbedonebyusingtheSystem.String.Concatmethod,or(mucheasier)usingthe+

operator:

stringfirst=”Hello”;

stringsecond=”World”;

stringconcat=first+second;//concat=”HelloWorld”

concat=String.Concat(first,second);//concat=“HelloWorld”

Section14.7:Changingthecaseofcharacterswithina String

TheSystem.Stringclasssupportsanumberofmethodstoconvertbetweenuppercaseandlowercasecharacters in a string.

• System.String.ToLowerInvariantisusedtoreturnaStringobjectconvertedtolowercase.
• System.String.ToUpperInvariantisusedtoreturnaStringobjectconvertedtouppercase.Note:Thereasontousetheinvariantversionsofthesemethodsistopreventproducingunexpectedculture- specific letters. This is explained here in detail.

Example:

strings=”MyString”;

s=s.ToLowerInvariant();//”mystring”

s=s.ToUpperInvariant();//“MYSTRING”

NotethatyoucanchoosetospecifyaspecificCulturewhenconvertingtolowercaseanduppercasebyusingthe String.ToLower(CultureInfo)and String.ToUpper(CultureInfo)methods accordingly.