Coding Problem Interview Series: How to Count Character Occurrences in a String?

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Today's question is:

How would you write a function to count the occurrence of a specific character in a given string?

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Comments

[Chantal]

Alright, so l tried this question in JavaScript cos that's the langguage l understand better hahahahaha.

Ok, so here we go:

function countOccurrences(string, char) {
  let count = 0;
  for (let i = 0; i < string.length; i++) {
    if (string.charAt(i) === char) {
      count++;
    }
  }
  return count;
}

So in this JavaScript function, string is the input string, and char is the character you want to count.

Let's try to put it into something real:

const myString = "Hello, World!";
const character = 'l';
const occurrenceCount = countOccurrences(myString, character);
console.log(`The character '${character}' occurs ${occurrenceCount} times in the string.`);

The Output:

The character 'l' occurs 3 times in the string.

The function uses a for loop to iterate over each character of the input string. It checks if the character at the current index is equal to the specified character. If there is a match, it increments the count variable. Finally, it returns the count of occurrences.

Ok, guys so that's it. I'm a junior too and l would love to learn from your corrections. Feel free to correct me!

[Parimal]

ChatGPT gave same answer and example you even as a junior you're coding on par with GPT, so you have got no reason to worry

[NLxDoDge]

In java something like this would do

String test = "Hello, World!";
String chr = "l";
long count = Arrays.stream(test.split("")).filter(chr::equals).count();
System.out.println(count);

And make it a bit more re-usable by putting it in a utility class as a function.

class StringUtils {
    public static long charCountInString(String input, String search) {
        if(input == null || search == null) {
            return 0L;
        }
        return Arrays.stream(input.split("")).filter(search::equals).count();
    }
}

Now, if you're more of a char guy you can do something like this

String test = "Hello, World!";
char chr = 'l';
long count = test.chars().filter(x -> x == chr).count();
System.out.println(count);

[Simon Goldin]

quick JS implementation:

const countLetter = (searchStr, letter) => searchStr.split(letter).length - 1;

countLetter('hello and happy Monday!', 'a'); // 3

[Nicole]

In python:

word = 'Test'
count = 0

for letter in word:
  if letter.lower() == 't':
    count += 1

print(count)

[Soumyadeep Dey ☑️]

🤔