how can i compute the length of an integer?

if i have

int = 12345;

length_int = 5;

???

[Jan]

What is the "length" of -1 and 0?

Answer 1

[Azzi Abdelmalek]

int=-123456789
max(ceil(log10(abs(int))),1)

[Christian Ziegler]

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)

Answer 2

[Sean de Wolski]

Edit

nnz(num2str(int) - '-')

[Friedrich]

Why this cast to an double array? Shouldn't

    numel(num2str(int))

be enough?

[Sean de Wolski]

Friedrich, neither work actually, consider -12345.

[Friedrich]

Good point Sean. But then

numel(num2str(abs(int)))

should do ;)

[Sean de Wolski]

arghh, you win!

Answer 3

[Davide Ferraro]

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]

why, it works:

 >> int = 12345678901234567890123

    numel(num2str(int))

int =

   1.2346e+22

ans =

    23