You can, for example, set the number of digits to be printed after the decimal in a floating point number. You can set the number of leading/trailing zeros in a number. You can print anything in hexadecimal without writing a conversion function. You can choose to print in decimal or scientific notation. The list goes on. I've searched, and I cannot find this ability in any C++ stream. Maybe I haven't searched well enough?
Well, what do you know...
How did I miss this?