Occurrences of substring in a string

Question

Why is the following algorithm not halting for me? (str is the string I am searching in, findStr is the string I am trying to find)

String str = \"helloslkhe         


        

Answer 1

A lot of the given answers fail on one or more of:

• Patterns of arbitrary length
• Overlapping matches (such as counting "232" in "23232" or "aa" in "aaa")
• Regular expression meta-characters

Here's what I wrote:

static int countMatches(Pattern pattern, String string)
{
    Matcher matcher = pattern.matcher(string);

    int count = 0;
    int pos = 0;
    while (matcher.find(pos))
    {
        count++;
        pos = matcher.start() + 1;
    }

    return count;
}

Example call:

Pattern pattern = Pattern.compile("232");
int count = countMatches(pattern, "23232"); // Returns 2

If you want a non-regular-expression search, just compile your pattern appropriately with the LITERAL flag:

Pattern pattern = Pattern.compile("1+1", Pattern.LITERAL);
int count = countMatches(pattern, "1+1+1"); // Returns 2