CODEWITHSUNDEEP
javastring
Zero
Zero

Reputation: 39

Finding index where char c starts in string s

I am writing a program with many methods for an assignment, and in one of the methods, I need to find the index where character c starts in string s. for example:

IN: sheep, h
OUT: 1

I have done this method but with two strings instead of a string and a character

public static int findInStr1(String s1, String s2) {
    for (int i = 0; i < s1.length() - s2.length(); i++) {
        boolean found = true;
        for (int j = 0; j < s2.length(); j++) {
            if (s1.charAt(i) != s2.charAt(j)) {
                found = false;
                break;
            }
        }
        if (found) {
            return i;
        }
    }
    return -1;  
}

I tried to move some things around to make it work with a char instead of a second string

public static int findInStr2(String s1, char c) {
    for (int i = 0; i < s1.length() - 1; i++) {
        boolean found = true;
        if (s1.charAt(i) != c) {
            found = false;
            break;
        }
        if (found) {
            return i;
        }
    }
    return -1;
}

but it always returns -1 no matter the input

Thanks in advance

Upvotes: 0

Views: 112

Answers (4)

Sainath S.R
Sainath S.R

Reputation: 3306

When its not found the first time around you set found to false and break , NOTE:break breaks out of the whole Loop not the if statement and hence -1 is returned

Try to write more compact and simpler code , The code below does exactly what you want ,

import java.util.*;

public class Found{

public static int findInStr2(String s1, char c) {
    for (int i = 0; i < s1.length(); i++)
     {
        if (s1.charAt(i)==c)
        {
        return i;
        }

     }
return -1;
}
public static void main(String[] args)
{

Found f=new Found();
int pos=Found.findInStr2("Hello",'o');
System.out.println("found at position"+(pos+1));
}//main ends

}//class ends

Upvotes: 1

amudhan3093
amudhan3093

Reputation: 750

Try this

for (int i = 0; i < s1.length() - 1; i++) {
     if (s1.charAt(i) == c) {
        return i;
     }
}
return -1;

Upvotes: 1

Gavin
Gavin

Reputation: 1767

I don't think you need the break statement. This is breaking you out of the for loop early.

You should be able to prove this by adding a system.out.println before the boolean found declaration to trace what your index is.

Upvotes: 1

corsiKa
corsiKa

Reputation: 82579

this line:

if (s1.charAt(i) != c) {

What does it do? It looks to see if the character is NOT the goal you're looking for. So in most cases, this triggers on the first character.

Next, you have a break statement BEFORE you have your return statement. Remember, break is just for loops, not for if statements. If you find it, don't use a found variable. Just return the index right then and there.

if (s1.charAt(i) == c) {
    return i;
}

Lastly, you have this as your for condition:

for (int i = 0; i < s1.length() - 1; i++)

You have to pick one or the other. Either use <= s1.length() - 1 or use < s1.length(). If you do both, you'll miss the last character. So "sheep", 'p' returns not found when it should return 4.

Upvotes: 3

Related Questions