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How to round off a number to certain significant figures using C++?

Could anyone tell me how to round off a number to certain significant
figures using C++?

For example, how to round off a number 12567 to 13000 (2 significant
Jul 22 '05 #1
2 9493
"Andy" <an*****@gmail. com> wrote...
Could anyone tell me how to round off a number to certain significant
figures using C++?

For example, how to round off a number 12567 to 13000 (2 significant

Look on http://groups.google.com for "implement rounding c++". You will
find plenty of solutions.

Jul 22 '05 #2
an*****@gmail.c om (Andy) wrote in message news:<ad******* *************** ***@posting.goo gle.com>...
Could anyone tell me how to round off a number to certain significant
figures using C++?

For example, how to round off a number 12567 to 13000 (2 significant

How would you do in on paper? Let me guess, you take the 3rd digit
(3, since you want to keep only 2 digits). If this third digit is
[0..4], set it and the digits following to 0. If the digit is
[5..9], increase the second digit (which may overflow, it it's 9)
and set the 3rd and following digits to 0.

Now, splitting a number into decimal digits is a bit tricky. You
need to know that the modulo operator in C++ is called '%', e.g.
25 modulo 10 is written (25%10)==5

Michiel Salters
Jul 22 '05 #3

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