How do I interpolate strings?

问题

I want to do the following in C# (coming from a Python background):

strVar = \"stack\"
mystr  = \"This is %soverflow\" % (strVar)

How do I replace the token inside the string with the value outside of it?

回答1:

string mystr = string.Format("This is {0}overflow", strVar);

And you could also use named parameters instead of indexes.

回答2:

This has been added as of C# 6.0 (Visual Studio 2015+).

Example:

var planetName = "Bob";
var myName = "Ford"; 
var formattedStr = $"Hello planet {planetName}, my name is {myName}!";
// formattedStr should be "Hello planet Bob, my name is Ford!"

This is syntactic sugar for:

var formattedStr = String.Format("Hello planet {0}, my name is {1}!", planetName, myName);

Additional Resources:

String Interpolation for C# (v2) Discussion

C# 6.0 Language Preview

回答3:

You can use string.Format to drop values into strings:

private static readonly string formatString = "This is {0}overflow";
...
var strVar = "stack";
var myStr = string.Format(formatString, "stack");

An alternative is to use the C# concatenation operator:

var strVar = "stack";
var myStr = "This is " + strVar + "overflow";

If you're doing a lot of concatenations use the StringBuilder class which is more efficient:

var strVar = "stack";
var stringBuilder = new StringBuilder("This is ");
for (;;)
{
    stringBuilder.Append(strVar); // spot the deliberate mistake ;-)
}
stringBuilder.Append("overflow");
var myStr = stringBuilder.ToString();

回答4:

C# 6.0

string mystr = $"This is {strVar}overflow";

回答5:

If you currently use Visual Studio 2015 with C# 6.0, try the following:

var strVar = "stack";

string str = $"This is {strVar} OverFlow";

that feature is called string interpolation.

回答6:

There is no operator for that. You need to use string.Format.

string strVar = "stack";
string mystr  = string.Format("This is {0}soverflow", strVar);

Unfortunately string.Format is a static method, so you can't simply write "This is {0}soverflow".Format(strVar). Some people have defined an extension method, that allows this syntax.

回答7:

Use string.Format:

string mystr = string.Format("This is {0}overflow", "stack");

回答8:

You should be using String.Format(). The syntax is a bit different, numerical placeholders are used instead.

Example:

String.Format("item {0}, item {1}", "one", "two")

Have a look at http://msdn.microsoft.com/en-us/library/system.string.format.aspx for more details.

回答9:

You have 2 options. You can either use String.Format or you can use the concatenation operator.

String newString = String.Format("I inserted this string {0} into this one", oldstring);

String newString = "I inserted this string " + oldstring + " into this one";

回答10:

There's one more way to implement placeholders with string.Replace, oddly helps in certain situations:

mystr = mystr.Replace("%soverflow", strVar);

回答11:

You can use the following way

String interpolation

The $ special character identifies a string literal as an interpolated string. e.g.

string name = "Mark";
string surname = "D'souza";
WriteLine($"Name :{name} Surname :{surname}" );//Name :Mark Surname :D'souza

An interpolated string is a string literal that might contain interpolated expressions. When an interpolated string is resolved to a result string, items with interpolated expressions are replaced by the string representations of the expression results.

String.Format

Use String.Format if you need to insert the value of an object, variable, or expression into another string.E.g.

WriteLine(String.Format("Name: {0}, Surname : {1}", name, surname));

回答12:

Use:

strVar = "stack"
mystr  = String.Format("This is {0}", strVar);

回答13:

You can accomplish this with Expansive: https://github.com/anderly/Expansive

来源：https://stackoverflow.com/questions/9354154/how-do-i-interpolate-strings

标签

string

string-interpolation