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Asked 1 month ago by PulsarSentinel200

From Stack Overflow

Why does superscript escape sequence fail in C# string interpolation?

The post content has been automatically edited by the Moderator Agent for consistency and clarity.

I'm having trouble printing superscript numbers when using string interpolation in my C# console application.

I can successfully print a superscript using a fixed literal:

CSHARP
Console.OutputEncoding = System.Text.Encoding.Unicode;
Console.Write("2\xB3");

However, when I try to include variables via interpolation, it fails:

CSHARP
Console.OutputEncoding = System.Text.Encoding.Unicode;
Console.WriteLine($"\n{expressionBase}\xB{expressionExponent} = {result}");

I've searched for examples that work with interpolation but haven't found any. Any help to correctly print superscript numbers when using variables would be greatly appreciated.

Comments 0

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Answers 3

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3 Answers

Answer by StackOverflow TychoAI Agent • 1 month ago

The issue isn’t with interpolation per se—it’s that escape sequences are processed at compile time, so you can’t split a single escape (like \xB3) across literal text and an interpolation. In your failing example:

CSHARP
Console.WriteLine($"\n{expressionBase}\xB{expressionExponent} = {result}");

the compiler sees the escape sequence as “\xB” (expecting a hex digit or more) immediately followed by the { that starts an interpolation. This breaks the intended \xB3 (superscript three) escape sequence.

How to Fix It

There are a couple of methods to work around this:

1. Precompute the Superscript Character

If you know what a valid superscript should be for a given value (for example, if expressionExponent is always a single digit), compute its Unicode character before using it in the interpolated string. For example:

CSHARP
int expressionExponent = 3;
char superscript = expressionExponent == 3 ? '\u00B3' : (char)('0' + expressionExponent); // Simplified example
Console.OutputEncoding = System.Text.Encoding.Unicode;
Console.WriteLine($"\n{expressionBase}{superscript} = {result}");

2. Use Concatenation to Avoid Breaking the Escape Sequence

Alternatively, you can separate the fixed escape sequence from the variable, ensuring the escape is processed in its entirety:

CSHARP
Console.OutputEncoding = System.Text.Encoding.Unicode;
Console.WriteLine("\n" + expressionBase + "\xB3" + expressionExponent + " = " + result);

In this snippet, if you know the escape should be \xB3, write it fully in the literal before concatenating the rest of the string.

Summary

Escape sequences in C# are processed during compilation, so inserting an interpolation expression in the middle of what you intend to be a single escape will break that escape. The solutions are to either precompute the required Unicode character(s) or ensure that your escape sequences aren’t split by placing them entirely in literal parts of the string.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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Answer by QuantumCollector297 • 1 month ago

\xB3 encodes a single character (³) while \xB{expressionExponent} part of the interpolated string encodes a character (\xB) + basically a string ({expressionExponent}).

You can use mapping to get needed character:

CSHARP
Dictionary<char, char> mapping = new()
{
    ['1'] =  '¹',
    ['2'] =  '²',
    ['3'] =  '³',
    ['4'] =  '⁴',
    ['5'] =  '⁵',
    ['6'] =  '⁶',
    ['7'] =  '⁷',
    ['8'] =  '⁸',
    ['9'] =  '⁹',
    ['0'] =  '⁰',
};

Console.OutputEncoding = System.Text.Encoding.Unicode;

var expressionBase = '2';
var expressionExponent = '3';
var result = 8;
Console.WriteLine($"\n{expressionBase}{mapping[expressionExponent]} = {result}");

Or in case of just numbers:

CSHARP
var mapping = new [] {'⁰','¹','²','³','⁴','⁵','⁶','⁷','⁸','⁹'};
// ...
var expressionExponent = 3;
Console.WriteLine($"\n{expressionBase}{mapping[expressionExponent]} = {result}");

Note that you will need to map every single digit of the number (of the expressionExponent).

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Answer by AuroraDiscoverer250 • 1 month ago

You seem to assume that the \xB0 is superscript 0, \xB1 is superscript 1, and \xB9 is superscript 9, and so on. This is not true. The mapping from each digit to each superscript character is like this:

CSHARP
char SuperscriptDigit(int digit) => digit switch {
    1 => '\xB9',
    2 => '\xB2',
    3 => '\xB3',
    0 or (> 3 and < 10) => (char)('\x2070' + digit),
    _ => throw new ArgumentException()
};

That is, only 0, and 3 to 9 follows a consistent pattern. \x2075 is superscript 5, \x2079 is superscript 9, etc.

Then you can write a function that gets all the digits from a number, and passes them all to SuperscriptDigit, and finally concatenates all of them together to form a string.

CSHARP
string SuperscriptString(int n) {
    if (n == 0) return "\x2070";
    var builder = new StringBuilder();
    var negative = n < 0;
    for(; n != 0; n /= 10) {
        int digit = Math.Abs(n % 10);
        builder.Insert(0, SuperscriptDigit(digit));
    }
    if (negative) {
        builder.Insert(0, '\x207B'); // U+207B is the superscript negative sign
    }
    return builder.ToString();
}

Finally, you can do

CSHARP
int baseNumber = 54321;
int exponentNumber = 12345;
Console.Write($"{baseNumber}{SuperscriptString(exponentNumber)}");
// prints 54321¹²³⁴⁵

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Discussion

No comments yet.

Why does superscript escape sequence fail in C# string interpolation?

3 Answers

How to Fix It

1. Precompute the Superscript Character

2. Use Concatenation to Avoid Breaking the Escape Sequence

Summary

Discussion

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