CODEWITHSUNDEEP
c#stringcastingchar
Ian R. O'Brien
Ian R. O'Brien

Reputation: 6930

How do I convert a single char to a string?

I'd like to enumerate a string and instead of it returning chars I'd like to have the iterative variable be of type string. This probably isn't possible to have the iterative type be a string so what is the most efficient way to iterate through this string?

Do I need to create a new string object with each iteration of the loop or can I perform a cast somehow?

String myString = "Hello, World";
foreach (Char c in myString)
{
    // what I want to do in here is get a string representation of c
    // but I can't cast expression of type 'char' to type 'string'
    String cString = (String)c; // this will not compile
}

Upvotes: 72

Views: 125359

Answers (12)

Brondahl
Brondahl

Reputation: 8596

I recently wanted to know which approach was the fastest, so I benchmarked 5 approaches.

The answer is that you should use new String(myChar,1), for the fastest times:

|           Method |      Mean |    Error |    StdDev | Rank |   Gen0 | Allocated |
|----------------- |----------:|---------:|----------:|-----:|-------:|----------:|
|        NewString |  10.65 ns | 0.502 ns |  1.473 ns |    1 | 0.0031 |      16 B |
|        AddString |  11.83 ns | 0.845 ns |  2.466 ns |    2 | 0.0030 |      16 B |
|     CharToString |  12.26 ns | 0.662 ns |  1.951 ns |    2 | 0.0030 |      16 B |
| NewStringPointer |  33.03 ns | 1.382 ns |  3.988 ns |    3 | 0.0030 |      16 B |
|      Interpolate | 119.31 ns | 5.351 ns | 15.525 ns |    4 | 0.0083 |      44 B |

Where the 5 methods are:

public string CharToString(char input) => input.ToString();
public string Interpolate(char input) => $"{input}";
public string AddString(char input) => input + "";
public string NewString(char input) => new String(input,1);
public string NewStringPointer(char input)
{
    unsafe
    {
        return new String(& input);
    }
}

Upvotes: 3

Alex
Alex

Reputation: 649

you can use + with empty string "", please check the below code: 

char a = 'A';
//a_str is a string, the value of which is "A".
string a_str = ""+a;

Upvotes: 1

Jim Balter
Jim Balter

Reputation: 16424

probably isn't possible to have the iterative type be a string

Sure it is:

foreach (string str in myString.Select(c => c.ToString())
{
...
}

Any of the suggestions in the other answers can be substituted for c.ToString(). Probably the most efficient by a small hair is c => new string(c, 1), which is what char.ToString() probably does under the hood.

Upvotes: 0

sean
sean

Reputation: 917

With C# 6 interpolation:

char ch = 'A';
string s = $"{ch}";

This shaves a few bytes. :)

Upvotes: 8

user1489240
user1489240

Reputation: 31

Why not this code? Won't it be faster?

string myString = "Hello, World";
foreach( char c in myString )
{
    string cString = new string( c, 1 );
}

Upvotes: 0

horgh
horgh

Reputation: 18563

Create an extension method:

public static IEnumerable<string> GetCharsAsStrings(this string value)
{
    return value.Select(c =>
           {
                //not good at all, but also a working variant
                //return string.Concat(c);

                return c.ToString();
           });
}

and loop through strings:

string s = "123456";
foreach (string c in s.GetCharsAsStrings())
{
    //...
}

Upvotes: 1

trebuchet
trebuchet

Reputation: 1481

Did you try:

String s = new String(new char[] { 'c' });

Upvotes: 0

Lukasz Madon
Lukasz Madon

Reputation: 15004

You have two options. Create a string object or call ToString method.

String cString = c.ToString();
String cString2 = new String(c, 1); // second parameter indicates
                                    // how many times it should be repeated

Upvotes: 15

Jeroen
Jeroen

Reputation: 4023

String cString = c.ToString();

Upvotes: 0

Mark Hall
Mark Hall

Reputation: 54562

Use the .ToString() Method

String myString = "Hello, World";
foreach (Char c in myString)
{
    String cString = c.ToString(); 
}

Upvotes: 90

Michael G
Michael G

Reputation: 6755

Create a new string from the char.

 String cString = new String(new char[] { c });

or

 String cString = c.ToString();

Upvotes: 4

Ian R. O&#39;Brien
Ian R. O&#39;Brien

Reputation: 6930

It seems that the obvious thing to do is this:

String cString = c.ToString()

Upvotes: 5

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