Count number of zero(0) using objective-c

Question

I want to count how many number of zero(0) before numeric number. Because I need to save those number which is present before numeric.

Exam:- suppose I have a number 0000102. So I want to calculate how many zero(0) before numeric start. In this exam we are see here is 4 zero's(0) are present. It is possible to calculate this?

how are you getting this number from? – f.khantsis Nov 06 '17 at 05:48 — f.khantsis, Nov 06 '17 at 05:48
From textfield. So number always dynamic. – Swarup Nov 06 '17 at 06:54 — Swarup, Nov 06 '17 at 06:54

score 2 · Answer 1 · answered Nov 06 '17 at 07:08

2

for (i=0;i<string.length;i++) 
 {  
   if ([[string characterAtIndex:i] intValue] <= 9 || [[string characterAtIndex:i] intValue] > 0 )
     {
       i++;
     }
    else
     {
      numerOfZeros++;
     }
}

answered Nov 06 '17 at 07:08

Neeraj Sonaro

346
1
16

score 1 · Accepted Answer · answered Nov 06 '17 at 05:53

1

int count = 0;
NSString *strr = @"0000102";
unichar findC;
for (int i = 0; i<strr.length; i++)
 {
    findC = [strr characterAtIndex:i];
     if (findC == '0')
          {
           count++;
          }
     else
           break;
  }
 NSLog(@"%d",count);

answered Nov 06 '17 at 05:53

Sangram Shivankar

3,535
3
26
38

Thanks @Sangram, But if string is like "00010002005", that time maybe out is 7's zero(0). right? So, i think it's a wrong arrroach. Remind me string is dynamic. please clarify. – Swarup Nov 06 '17 at 06:54
NO check solution once again it will give you 3 – Sangram Shivankar Nov 06 '17 at 07:37
Yes @sarang, you are right. not count all zero(0). thanks – Swarup Nov 06 '17 at 08:11

score 0 · Answer 3 · edited Jun 20 '20 at 09:12

0

Recursive approach for a one liner:

@implementation NSString (category)

- (NSUInteger)zeroPrefixCount
{
    return [string hasPrefix:@"0"] ? 1 + [[string substringFromIndex:1] zeroPrefixCount] : 0;
}

@end

This is not an optimal solution, performance-wise, but it's typical of your first days at programming classes.

usage

// x will be 4
NSUInteger x = [@"0000102" zeroPrefixCount];

edited Jun 20 '20 at 09:12

Community

1
1

answered Nov 06 '17 at 06:30

Cœur

37,241
25
195
267

Hi @Cœur, this approach is quite right. But if user put 0023405, then I think you code's output will be wrong – Swarup Nov 06 '17 at 06:57
@SanjibDe why? No, output will be correct, it will return 2. Try it. – Cœur Nov 06 '17 at 09:40
@ Cœur, I am so sorry, yes you are also right. Thanks for replying me – Swarup Nov 06 '17 at 10:37

score -1 · Answer 4 · answered Nov 06 '17 at 07:18

I recommend you to save this kind of numbers as String itself and no need to further evaluate how many zeros are there rather do a string comparison if needed.

If you really want to count zeros in your number then you can consider converting it to a string and use NSRange and NSString helper methods to get what you want. Similar situation is answered here.

search if NSString contains value

Count number of zero(0) using objective-c

4 Answers4

usage