[Unity]StringBuilder
在C#中，字符串string还是一种不可变的引用类型，在对字符串进行操作修改后，原有的字符串内存数据会被回收，代码所拿到的其实是一个新的字符串对象。在需要对字符串进行大规模的修改时，会造成GC性能的损耗，C#的标准库中提供了一个StringBuilder类用来弥补string的这个缺点。
点击查看代码
//Unity的API
[DefaultMember("Chars")]
public sealed class StringBuilder : ISerializable
{
public StringBuilder();
public StringBuilder(int capacity);
public StringBuilder(string value);
public StringBuilder(int capacity, int maxCapacity);
public StringBuilder(string value, int capacity);
public StringBuilder(string value, int startIndex, int length, int capacity);
public char this[int index] { get; set; }
public int Capacity { get; set; }
public int Length { get; set; }
public int MaxCapacity { get; }
public StringBuilder Append(char value, int repeatCount);
[CLSCompliant(false)]
public StringBuilder Append(char* value, int valueCount);
public StringBuilder Append(byte value);
public StringBuilder Append(bool value);
[CLSCompliant(false)]
public StringBuilder Append(ulong value);
[CLSCompliant(false)]
public StringBuilder Append(uint value);
[CLSCompliant(false)]
public StringBuilder Append(ushort value);
public StringBuilder Append(char value);
public StringBuilder Append(StringBuilder value);
public StringBuilder Append(string value, int startIndex, int count);
public StringBuilder Append(string value);
public StringBuilder Append(StringBuilder value, int startIndex, int count);
[CLSCompliant(false)]
public StringBuilder Append(sbyte value);
public StringBuilder Append(ReadOnlySpan<char> value);
public StringBuilder Append(object value);
public StringBuilder Append(long value);
public StringBuilder Append(int value);
public StringBuilder Append(short value);
public StringBuilder Append(double value);
public StringBuilder Append(char[] value);
public StringBuilder Append(char[] value, int startIndex, int charCount);
public StringBuilder Append(float value);
public StringBuilder Append(decimal value);
public StringBuilder AppendFormat(string format, params object[] args);
public StringBuilder AppendFormat(string format, object arg0, object arg1, object arg2);
public StringBuilder AppendFormat(IFormatProvider provider, string format, object arg0, object arg1, object arg2);
public StringBuilder AppendFormat(string format, object arg0);
public StringBuilder AppendFormat(IFormatProvider provider, string format, params object[] args);
public StringBuilder AppendFormat(IFormatProvider provider, string format, object arg0, object arg1);
public StringBuilder AppendFormat(IFormatProvider provider, string format, object arg0);
public StringBuilder AppendFormat(string format, object arg0, object arg1);
public StringBuilder AppendJoin<T>(string separator, IEnumerable<T> values);
public StringBuilder AppendJoin(string separator, params string[] values);
public StringBuilder AppendJoin(string separator, params object[] values);
public StringBuilder AppendJoin(char separator, params object[] values);
public StringBuilder AppendJoin(char separator, params string[] values);
public StringBuilder AppendJoin<T>(char separator, IEnumerable<T> values);
public StringBuilder AppendLine();
public StringBuilder AppendLine(string value);
public StringBuilder Clear();
public void CopyTo(int sourceIndex, char[] destination, int destinationIndex, int count);
public void CopyTo(int sourceIndex, Span<char> destination, int count);
public int EnsureCapacity(int capacity);
public bool Equals(StringBuilder sb);
public bool Equals(ReadOnlySpan<char> span);
[CLSCompliant(false)]
public StringBuilder Insert(int index, ulong value);
[CLSCompliant(false)]
public StringBuilder Insert(int index, uint value);
[CLSCompliant(false)]
public StringBuilder Insert(int index, ushort value);
public StringBuilder Insert(int index, string value, int count);
public StringBuilder Insert(int index, float value);
[CLSCompliant(false)]
public StringBuilder Insert(int index, sbyte value);
public StringBuilder Insert(int index, ReadOnlySpan<char> value);
public StringBuilder Insert(int index, string value);
public StringBuilder Insert(int index, int value);
public StringBuilder Insert(int index, bool value);
public StringBuilder Insert(int index, byte value);
public StringBuilder Insert(int index, long value);
public StringBuilder Insert(int index, char value);
public StringBuilder Insert(int index, object value);
public StringBuilder Insert(int index, char[] value, int startIndex, int charCount);
public StringBuilder Insert(int index, decimal value);
public StringBuilder Insert(int index, double value);
public StringBuilder Insert(int index, short value);
public StringBuilder Insert(int index, char[] value);
public StringBuilder Remove(int startIndex, int length);
public StringBuilder Replace(char oldChar, char newChar, int startIndex, int count);
public StringBuilder Replace(string oldValue, string newValue);
public StringBuilder Replace(string oldValue, string newValue, int startIndex, int count);
public StringBuilder Replace(char oldChar, char newChar);
public override string ToString();
public string ToString(int startIndex, int length);
}
从上面的API我们可以看出来StringBuilder具有值类型兼容性、增删改查、文本格式化等功能。当对StringBuilder修改后，返回的是原来的StringBuilder对象，重复使用StringBuilder实例，可以减少不必要的内存分配。
StringBuilder的使用也十分简单，一个简单的例子：将一个字符串数组的元素拼接成一个字符串，并以/分隔
点击查看代码
List<string> stringArr = new List<string> { "A", "B", "C" };
StringBuilder sb = new StringBuilder();
for (int i = 0; i < stringArr.Count; i++)
{
sb.Append(stringArr[i] + "/");
}
string result = sb.ToString();