创建一个StringBuilder具有大容量

Question

我发现下面的代码在我老板的项目：

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

之前我叫他出来就可以了，我想确认该行是否实际上是设置一兆字节（或Unicode中的两兆字节）内存，而不是那一个stringbuilder？

Answer 1

初始化长度1000000

的Char()所以在存储器所需的实际尺寸是2000000字节 =〜2 MB由于炭是unicode，需要2个字节。

编辑：万一你的老板不相信，这反映了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); 
    } 
} 

Answer 2

您可以尝试在拨款前后拨打GC.GetTotalMemory()，查看是否增加。注意：这不是一个好的，科学的方式来做到这一点，但可能证明你的观点。