Chapter15:StringInterpolation

Section15.1:Formatdatesinstrings

vardate=newDateTime(2015,11,11);

varstr=$”It’s{date:MMMMd,yyyy},makeawish!”;

System.Console.WriteLine(str);

YoucanalsousetheDateTime.ToStringmethodtoformattheDateTimeobject.Thiswillproducethesameoutput as the code above.

vardate=newDateTime(2015,11,11);

varstr=date.ToString(“MMMMd,yyyy”);

str=”It’s”+str+”,makeawish!”;

Console.WriteLine(str);

Output:

It’sNovember11,2015,makeawish!

LiveDemoon.NETFiddle

LiveDemousingDateTime.ToString

Note:MMstandsformonthsandmmforminutes.Beverycarefulwhenusingtheseasmistakescan introduce bugs that may be difficult to discover.

Section15.2:Paddingtheoutput

String can be formatted to accept a padding parameter that will specify how many character positions the inserted string will use :

${value,padding}

NOTE:Positivepaddingvaluesindicateleftpaddingandnegativepaddingvaluesindicaterightpadding.

LeftPadding

A left padding of 5 (adds 3 spaces before the value of number, so it takes up a total of 5 character positions in the resulting string.)

varnumber=42;

varstr=$”Theanswertolife,theuniverseandeverythingis{number,5}.”;

//stris”Theanswertolife,theuniverseandeverythingis                                           42.”;

//                                                                                                                                            ^^^^^

System.Console.WriteLine(str);

Output:

Theanswertolife,theuniverseandeverythingis 42.

LiveDemoon.NETFiddle

RightPadding

Rightpadding,whichusesanegativepaddingvalue,willaddspacestotheendofthecurrentvalue.

varnumber=42;

varstr=$”Theanswerto life,theuniverseandeverything is${number,-5}.”;

//stris”Theanswertolife,theuniverseandeverythingis42                                          .”;

//                                                                                                                                            ^^^^^

System.Console.WriteLine(str);

Output:

Theanswertolife,theuniverseandeverythingis42                                 .

LiveDemoon.NETFiddle

PaddingwithFormatSpecifiers

Youcanalsouseexistingformattingspecifiersinconjunctionwithpadding.

varnumber=42;

varstr=$”Theanswertolife,theuniverseandeverythingis${number,5:f1}”;

//stris”Theanswertolife,theuniverseandeverythingis42.1“;

//             ^^^^^

LiveDemoon.NETFiddle

Section15.3:Expressions

Fullexpressionscanalsobeusedininterpolatedstrings.

varStrWithMathExpression=$”1+2={1+2}”;//->”1+2=3″

stringworld=”world”;

varStrWithFunctionCall=$”Hello,{world.ToUpper()}!”;//->”Hello,WORLD!”

LiveDemoon.NETFiddle

Section15.4:Formattingnumbersinstrings

Youcanuseacolonandthestandardnumericformatsyntaxtocontrolhownumbersareformatted.

vardecimalValue=120.5;

varasCurrency=$”Itcosts{decimalValue:C}”;

//Stringvalueis”Itcosts$120.50″(dependingonyourlocalcurrencysettings)

varwithThreeDecimalPlaces=$”Exactly{decimalValue:F3}”;

//Stringvalueis”Exactly120.500″

varintegerValue=57;

varprefixedIfNecessary=$”{integerValue:D5}”;

//Stringvalueis”00057″

LiveDemoon.NETFiddle

Section15.5:SimpleUsage

varname=”World”;

varstr=$”Hello,{name}!”;

//strnowcontains:”Hello,World!”;

Behindthescenes

Internallythis

$”Hello,{name}!”

Willbecompiledtosomethinglikethis:

string.Format(“Hello,{0}!”,name);