Question

I’ve found the following code in my boss’s project:

Dim strBuilder As New System.Text.StringBuilder("", 1000000)

Before I call him out on it, I’d like to confirm whether this line actually sets a megabyte (or two megabytes in Unicode?) of memory aside for that one stringbuilder?

Answer 1

That initializes a Char() of length 1000000.

So the actual size needed in memory is 2000000 Bytes = ~2 MB since a char is unicode and needs 2 bytes.

Edit: Just in case your boss doesn’t believe, this is reflected with ILSpy:

// System.Text.StringBuilder
[SecuritySafeCritical]
public unsafe StringBuilder(string value, int startIndex, int length, int capacity)
{
    if (capacity < 0)
    {
        throw new ArgumentOutOfRangeException("capacity", Environment.GetResourceString("ArgumentOutOfRange_MustBePositive", new object[]
        {
            "capacity"
        }));
    }
    if (length < 0)
    {
        throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_MustBeNonNegNum", new object[]
        {
            "length"
        }));
    }
    if (startIndex < 0)
    {
        throw new ArgumentOutOfRangeException("startIndex", Environment.GetResourceString("ArgumentOutOfRange_StartIndex"));
    }
    if (value == null)
    {
        value = string.Empty;
    }
    if (startIndex > value.Length - length)
    {
        throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_IndexLength"));
    }
    this.m_MaxCapacity = 2147483647;
    if (capacity == 0)
    {
        capacity = 16;
    }
    if (capacity < length)
    {
        capacity = length;
    }
    this.m_ChunkChars = new char[capacity];
    this.m_ChunkLength = length;
    fixed (char* ptr = value)
    {
        StringBuilder.ThreadSafeCopy(ptr + (IntPtr)startIndex, this.m_ChunkChars, 0, length);
    }
}