Hi

i need some help

i wanna have the cin function which just scans a number and not a letter

if i tip a letter i need a cout something like << " thats not a number"

maybe some help ?

greetz
Neme

"According to the IEEE standard, NaN values have the odd property that comparisons involving them are always false. That is, for a float f, f != f will be true only if f is NaN." ( took from stackoverflow )

so i guess you could use:

isn't there a function to check if it's a digit? or check the unicode/ascii values?

wouldnt be that hard.

if you need to see if its a digit just check if the character ranges between (int)48 - 57 or w/e and if you need to turn it into its actual value just minus 48 from its character value.

Just use scanf() from stdio.h

Example:



More about scanf() here: http://www.cplusplus.com/reference/clibrary/cstdio/scanf/

The whole site is very helpful when writing C/C++

Edit: Fixed a typo

This post was edited by Jupelius on Jun 15 2012 08:58am

@StormHasHe: It would be better if you didn't offer advice on topics you clearly have no idea about.

In C++03, it's not that straightforward, the best idea I came up with is http://ideone.com/EJ7LQ

If you can use C++11, you can use functions like stoi and get something like this http://ideone.com/47LGS

I admit, neither is very reader-friendly, but it'd be trivial to write your own template function that'd try to convert strings from an istream.