The ToLong method is a static extension method provided by the SandboxSystemExtensions class. It is used to convert a string representation of a number into a 64-bit signed integer (Int64). If the conversion fails, it returns a default value specified by the user.

To use the ToLong method, call it on a string instance. Provide the string to be converted and a default Int64 value that will be returned if the conversion is unsuccessful.

Example usage:

string numberString = "123456789";
long defaultValue = 0;
long result = numberString.ToLong(defaultValue);

In this example, result will be 123456789 if the conversion is successful. If numberString cannot be converted to a Int64, result will be 0.