StringBuilder.Append Method (Double)
Appends the string representation of a specified double-precision floating-point number to the end of this instance.
Assembly: mscorlib (in mscorlib.dll)
Enlarging the value of this instance would exceed its maximum capacity.
The method modifies the existing instance of this class; it does not return a new class instance. Because of this, you can call a method or property on the existing reference and you do not have to assign the return value to a StringBuilder object, as the following example illustrates.
The capacity of this instance is adjusted as needed.