How to get number of digits in int variable?

[guidosh]

Hello,

I'm trying to write a printf statement that sets the field width when
printing a number. I'm using this:

printf("%*", fieldwidth, num_to_print);

However, I can't figure out how to get the number of digits in the
number (which I would then assign to the 'fieldwidth' variable above).

I know I don't have to explicitly set the field width with printf, but
I would like very much to know how to discover it.

Can anyone suggest how I might get the number of digits for a numeric
variable?

Thanks...

[Charles Richmond]

gu*****@gmail.c om wrote:

Hello,

I'm trying to write a printf statement that sets the field width when
printing a number. I'm using this:

printf("%*", fieldwidth, num_to_print);

However, I can't figure out how to get the number of digits in the
number (which I would then assign to the 'fieldwidth' variable above).

I know I don't have to explicitly set the field width with printf, but
I would like very much to know how to discover it.

Can anyone suggest how I might get the number of digits for a numeric
variable?

The integer part of the log base 10 of MAXINT will tell you how
many digits are maximum in an integer. Add one more for a negative
sign.

If you know the number of bits representing a number (*not* counting
the sign bit), divide this by approximately 3.32 (1 / log 2) to get
the number of decimal digits that can be represented. The fractional
part (if non-zero) means that one more digit can represent numbers
somewhat less than "9".

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