TheAlgorithms/C-Sharp · error · ArgumentOutOfRangeException

Load factor must be greater than 0

Error message

Load factor must be greater than 0

What it means

The HashTable constructor throws ArgumentOutOfRangeException when the loadFactor parameter is zero or negative. Load factor controls how full the table may get before resizing; a non-positive value makes the resize threshold meaningless (zero or negative), so the library rejects it eagerly at construction time.

Solutions

1. Pass a load factor greater than 0 and <= 1 (a common choice is 0.75).
2. If the value comes from config, validate with double.TryParse and fall back to 0.75 when missing or out of range.
3. Guard derived values: Math.Max(0.01, Math.Min(1.0, computedLoadFactor)) before constructing.

Example fix

// before
var ht = new HashTable<string, int>(16, config.LoadFactor); // LoadFactor may be 0
// after
var lf = config.LoadFactor > 0 && config.LoadFactor <= 1 ? config.LoadFactor : 0.75;
var ht = new HashTable<string, int>(16, lf);

if (double.IsNaN(loadFactor) || loadFactor <= 0 || loadFactor > 1)
    throw new ArgumentOutOfRangeException(nameof(loadFactor), "Load factor must be in (0, 1]");

static bool IsValidLoadFactor(double lf) => !double.IsNaN(lf) && lf > 0 && lf <= 1;

try { var ht = new HashTable<string,int>(cap, loadFactor); }
catch (ArgumentOutOfRangeException ex) when (ex.ParamName == "loadFactor")
{
    loadFactor = 0.75; // fallback default
}

When it happens

Trigger: Calling new HashTable<TKey,TValue>(capacity, loadFactor) with loadFactor <= 0, e.g. new HashTable<string,int>(10, 0) or new HashTable<string,int>(10, -0.5f), or passing a computed/derived load factor expression that evaluates to zero or negative.

Common situations: Configuration values read from app settings or environment variables where the load factor is parsed into a double that defaults to 0 when the setting is missing or fails to parse; math that computes a ratio like used/total yielding 0 on an empty table and being fed straight into the constructor.

Related errors

• Load factor must be less than or equal to 1
• k must be at least 1.
• Number of colors must be positive.
• Board size must be positive.
• Capacity must be greater than 0

AI-assisted analysis of TheAlgorithms/C-Sharp@96e2905cab (2026-09-13). Data as JSON: /api/errors/8b32815a15d78946. Report an issue: GitHub.

Appendix: source

Thrown at DataStructures/Hashing/HashTable.cs:100

    /// <param name="loadFactor">Load factor of the hash table.</param>
    /// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="capacity"/> is less than or equal to 0.</exception>
    /// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="loadFactor"/> is less than or equal to 0.</exception>
    /// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="loadFactor"/> is greater than 1.</exception>
    /// <remarks>
    /// <paramref name="capacity"/> is rounded to the next prime number.
    /// </remarks>
    /// <see cref="PrimeNumber.NextPrime(int, int, bool)"/>
    /// <see cref="PrimeNumber.IsPrime(int)"/>
    public HashTable(int capacity = DefaultCapacity, float loadFactor = DefaultLoadFactor)
    {
        if (capacity <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(capacity), "Capacity must be greater than 0");
        }

        if (loadFactor <= 0)
        {
            throw new ArgumentOutOfRangeException(nameof(loadFactor), "Load factor must be greater than 0");
        }

        if (loadFactor > 1)
        {
            throw new ArgumentOutOfRangeException(nameof(loadFactor), "Load factor must be less than or equal to 1");
        }

        this.capacity = PrimeNumber.NextPrime(capacity);
        this.loadFactor = loadFactor;
        threshold = (int)(this.capacity * loadFactor);
        entries = new Entry<TKey, TValue>[this.capacity];
    }

    /// <summary>
    /// Adds a key-value pair to the hash table.
    /// </summary>
    /// <param name="key">Key to add.</param>
    /// <param name="value">Value to add.</param>

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