# how can i compute the length of an integer?

77 views (last 30 days)
Zaza on 4 Jan 2013
Commented: Christian Ziegler on 14 Nov 2020
if i have
int = 12345;
length_int = 5;
???
Jan on 4 Jan 2013
What is the "length" of -1 and 0?

Azzi Abdelmalek on 4 Jan 2013
Edited: Azzi Abdelmalek on 4 Jan 2013
int=-123456789
max(ceil(log10(abs(int))),1)
Christian Ziegler on 14 Nov 2020
this doesn't work for 10, 100, 1000...
for example max(ceil(log10(abs(10))),1) equals 1 but it should be 2
simple fix:
int = 10;
max(ceil(log10(abs(int)+1)),1)

Sean de Wolski on 4 Jan 2013
Edited: Sean de Wolski on 4 Jan 2013
Edit
nnz(num2str(int) - '-')
Sean de Wolski on 4 Jan 2013
arghh, you win!

Davide Ferraro on 4 Jan 2013
Casting the variable into a string may be risky because you may get to "unexpected" cases such as:
int = 12345678901234567890123
numel(num2str(int))
ans =
12
You may consider a numeric approach using LOG10: floor(log10(int))+1 all numbers between 10 and 100 will have a LOG10 between 1 and 2 so you can use FLOOR to get the lower value (1 in this case) and then you need to add the value 1 cause you are trying to compute the number of digits and not the power of ten.
G A on 4 Jan 2013
Edited: G A on 4 Jan 2013
why, it works:
>> int = 12345678901234567890123
numel(num2str(int))
int =
1.2346e+22
ans =
23

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