System.Text.StringBuilder.EnsureCapacity C# (CSharp) Method

		public int EnsureCapacity (int capacity) 
		{
			if (capacity < 0)
				throw new ArgumentOutOfRangeException ("Capacity must be greater than 0." );

			if( capacity <= _str.Length )
				return _str.Length;

			InternalEnsureCapacity (capacity);

			return _str.Length;
		}

 public static StringBuilder AppendEscapedJson(StringBuilder builder, string value)
 {
   if (value == null) return builder;
   builder.EnsureCapacity(builder.Length + value.Length + 5);
   for (var i = 0; i < value.Length; i++)
   {
     switch (value[i])
     {
       case '\t':
         builder.Append(@"\t");
         break;
       case '\n':
         builder.Append(@"\n");
         break;
       case '\r':
         builder.Append(@"\r");
         break;
       case '"':
         builder.Append(@"\""");
         break;
       case '\\':
         builder.Append(@"\\");
         break;
       default:
         builder.Append(value[i]);
         break;
     }
   }
   return builder;
 }