How to Count Number of Occurrences of a Given Character in a String

#1

Post by vaibhavmule » Sun, Nov 25, 2018, 3:46 PM UTC

How to Count Number of Occurrences of a Given Character in a String
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Re: How to Count Number of Occurrences of a Given Character in a String

#2

Post by 11235813213455 » Sun, Nov 25, 2018, 4:41 PM UTC

That method doesn't really make sense, you could easily reuse an existing one: e.g. in JS: str.match(RegExp(char, 'g'))?.length, or [...str].filter(c => c === char).length

Re: How to Count Number of Occurrences of a Given Character in a String

#3

Post by hannofcart » Sun, Nov 25, 2018, 4:44 PM UTC

How did this make it to HN front-page? Curious.

Re: How to Count Number of Occurrences of a Given Character in a String

#4

Post by minimaxir » Sun, Nov 25, 2018, 4:45 PM UTC

hannofcart wrote: post #3

How did this make it to HN front-page? Curious.

The weekend HN algorithm is very weird and frustrating.

Re: How to Count Number of Occurrences of a Given Character in a String

#5

Post by Someone » Sun, Nov 25, 2018, 4:49 PM UTC

11235813213455 wrote: post #2

That method doesn't really make sense, you could easily reuse an existing one: e.g. in JS: str.match(RegExp(char, 'g'))?.length, or [...str].filter(c => c === char).length

That call allocates a regular expression and, even ignoring that allocation, will struggle to be as fast as the count call.

(On top of that, I think it’s buggy. It won’t count character occurrences if char is a special character such as ‘^’ or ‘.’)