## Counting the number of digits

on 3 Jul 2011

### bym (view profile)

Hi,

how can I compute the number of digits A=[12875] how can I get 5 as the number of digits in A?

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### bym (view profile)

on 3 Jul 2011

One way:

```numel(num2str(A))
```

Paulo Silva

### Paulo Silva (view profile)

on 3 Jul 2011

I made the stupid mistake of using -'0' when it wasn't needed so I'm voting on your answer and removing mine.

Oleg Komarov

### Oleg Komarov (view profile)

on 3 Jul 2011

Fails with decimals. Ex: n = 99.3;

Walter Roberson

### Walter Roberson (view profile)

on 15 Jul 2011

Fails with negative numbers too.

### Oleg Komarov (view profile)

on 3 Jul 2011

To count integer part

```ceil(log10(abs(A)))
```

Edit

```floor(log10(abs(A)+1)) + 1
```

Walter Roberson

### Walter Roberson (view profile)

on 15 Jul 2011

Fails on [-1,1] and all exact powers of 10.

Jan Simon

### Jan Simon (view profile)

on 15 Jul 2011

ceil(log10(abs(A) + 1)) ?

Walter Roberson

### Walter Roberson (view profile)

on 15 Jul 2011

Fails on 0, Jan.

Over integral values:

ceil(log10(max(1,abs(A)+1)))

Over real numbers,

ceil(log10(max(1,abs(A)*(1+eps))))

I think.

on 16 Aug 2013
Edited by Turner

### Turner (view profile)

on 19 Aug 2013

Will do the trick for all nonzero integers:

```fix(abs(log10(abs(A))))+1
```

For a 10,000 iteration benchmark with some above answers:

Jaymin= 1.423717 seconds; Stephanie= 0.476135 seconds; Mine= 0.000878 seconds

If you don't expect 0s to appear, this is the fastest and most accurate method. Only works for decimals that satisfy -1<A<1.

### Jaymin (view profile)

on 13 Dec 2012

Long, but it gets the job done.

numel(num2str(A))-numel(strfind(num2str(A),'-'))-numel(strfind(num2str(A),'.'))

### fugue (view profile)

on 26 May 2013
```numel(num2str(fix(abs(A))))
```