Exercise 13: Count Occurrences of Substring
Problem Statement
Function `countOccurrences(str, substr)` banao jo string me substring ki count return kare.
Example: countOccurrences("hello hello", "hello") => 2
Sample Output:
countOccurrences("hello hello", "hello") => 2
countOccurrences("aaa", "aa") => 2Solution
const countOccurrences = (str, substr) => {
const s = String(str ?? ""), sub = String(substr ?? "");
if (sub.length === 0) return 0;
return (s.match(new RegExp(sub.replace(/[.*+?^${}()|[\]\\]/g, "\\$&"), "g")) || []).length;
};Explanation
Overall Goal:
- String me substring ki frequency count karna.
Real world:
- Text analysis: pattern counting.
- Search: occurrence counting.