I'm learning Java as I complete CodingBat exercises, and I want to start using regular expressions to solve some level 2 String problems. I'm currently trying to solve this problem:
Return the number of times that the string "code" appears anywhere in the given string, except we'll accept any letter for the 'd', so "cope" and "cooe" count.
countCode("aaacodebbb") → 1
countCode("codexxcode") → 2
countCode("cozexxcope") → 2
And here is the piece of code I wrote (which doesn't work, and I'd like to know why):
public int countCode(String str) {
int counter = 0;
for (int i=0; i<str.length()-2; i++)
if (str.substring(i, i+3).matches("co?e"))
counter++;
return counter;
}
I'm thinking that maybe the matches method isn't compatible with substring, but I'm not sure.
You need to use the regular expression syntax. In this case you want "co\\\\we"
, where \\\\w
means any letter.
BTW you can do
public static int countCode(String str) {
return str.split("co\\we", -1).length - 1;
}
Try using this in the if statement. Unless I'm mixing up Java rules with PHP, then it needs to be +4 rather than +3.
str.substring(i, i+4)
public int countCode(String str) {
int count=0; // created a variable to count the appearance of "coe" in the string because d doesn't matter.
for(int i=0;i<str.length()-3;i++){
if(str.charAt(i)=='c'&&str.charAt(i+1)=='o'&&str.charAt(i+3)=='e'){
++count; // increment count if we found 'c' and 'o' and 'e' in the string.
}
}
return count; // returing the number of count 'c','o','e' appeared in string.
}
public class MyClass {
public static void main(String[] args) {
String str="Ramcodecopecofeacolecopecofeghfgjkfjfkjjcojecjcj BY HARSH RAJ";
int count=0;
for (int i = 0; i < str.length()-3; i++) {
if((str.substring(i, i+4)).matches("co[\\w]e")){
count++;
}
}
System.out.println(count);
}
}
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