Question

in c or c++
the function comlen is defined such

int comlen(char *p,char *q){
   int i=0;
   while  *p && (*p++==*q++)
      i++;
   return i;
}

Is this code equivalent of this function?

int comlen(String s,String m){
   int  i=0;
   while (i<s.length() && s.charAt(i)==m.charAt(i)){
      i++;
   }
   return i;
}

Answer 1

Would I be correct in assuming this function returns how many characters are identical starting at the beginning of the string?

You may want to check out Apache Commons Lang StringUtils and its indexOfDifference method.

Otherwise, this function should work (but I haven’t tested it):

public int comlen(CharSequence s, CharSequence m) {
    int end = s.length() > m.length() ? m.length() : s.length();
    int i = 0;
    while (i < end && s.charAt(i) == m.charAt(i)) {
        i++;
    }
    return i;
}

Note that CharSequence is an interface that is used by String, StringBuffer, and StringBuilder rather than just String.