code to convert from desimal to hexsa desimal

[walaetoom]

i want to write program that show how memory saved the floating number and calculate the speed of computer to print 1000 floating number

[whodgson]

Addressing your title:
I think they are called 'format manipulators'.

int n=15;
cout<<hex<<n;// will print f or F.
// or
cin>>hex>>n;//will input f or F.

For the rest you would need to post some code with specific queries to obtain further assistance.

[RRick]

To figure out how long it takes to convert the numbers, you have a couple of options. The simplest way is to just get a stopwatch out and time the program. In linux, the date function works well, but has a low resolution of only seconds. For this to work, you need to run a lot more than just 1000 conversions.

You can also check run times from within the program. In this case, you'll need a system routine that works with time. On windows, GetSystemTimeAs FileTime works and on linux, try gettimeofday. You still have to figure out how to subtract one time from another.