TheAlgorithms/C-Sharp · error · ArgumentException

number must be positive

Error message

number must be positive

What it means

BitArray.Compile(int) throws ArgumentException when the number is zero or negative. Only positive integers have a well-defined unsigned binary representation for this implementation, so the method rejects number <= 0 as its first precondition before converting to binary with Convert.ToString(number, 2).

Solutions

1. Validate `number > 0` before calling Compile and handle zero/negative explicitly
2. If zero must be representable, write the bits manually (e.g., compile the string "0") rather than using Compile(int)
3. Catch ArgumentException when caller-supplied values are untrusted
4. Clamp or map non-positive inputs to a valid domain before invoking

Example fix

// before
bits.Compile(count); // throws when count == 0
// after
if (count > 0)
{
    bits.Compile(count);
}
else
{
    bits.Compile("0"); // explicit zero representation
}

if (number > 0) bitArray.Compile(number); else /* handle zero/negative */;

static bool IsCompilable(int n) => n > 0 && Convert.ToString(n, 2).Length <= bitArray.Length;

try { bitArray.Compile(number); } catch (ArgumentException) { /* non-positive or too big */ }

When it happens

Trigger: `bitArray.Compile(0)` or `bitArray.Compile(negativeInt)` — commonly from counter variables that start at 0, default/uninitialized int fields, or signed subtraction results.

Common situations: Passing an accumulator that never incremented; feeding a difference (a-b) that came out negative; default(struct) initialization yielding 0; parsing user input that permits zero.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• Sequence must been greater than or equal to 1
• sequence must be not longer than the bit array length
• Provided number is too big
• Value is too big to fit into Int64
• Value is too big to fit into Int32

AI-assisted analysis of TheAlgorithms/C-Sharp@96e2905cab (2026-09-13). Data as JSON: /api/errors/0b1c819e46ca80d6. Report an issue: GitHub.

Appendix: source

Thrown at DataStructures/BitArray.cs:566

        // actual compile procedure.
        for (var i = 0; i < sequence.Length; i++)
        {
            field[i] = sequence[i] == '1';
        }
    }

    /// <summary>
    ///     Compiles integer number into the inner data structure.
    ///     Assumes: the number must have the same bit length.
    /// </summary>
    /// <param name="number">A positive integer number.</param>
    public void Compile(int number)
    {
        // precondition I
        if (number <= 0)
        {
            throw new ArgumentException($"{nameof(number)} must be positive");
        }

        // converts to binary representation
        var binaryNumber = Convert.ToString(number, 2);

        // precondition II
        if (binaryNumber.Length > field.Length)
        {
            throw new ArgumentException("Provided number is too big");
        }

        // for appropriate scaling
        if (binaryNumber.Length < field.Length)
        {
            var difference = field.Length - binaryNumber.Length;
            binaryNumber = new string('0', difference) + binaryNumber;
        }

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