Thread: First string is a substring of another

I need to write a User Defined Method which
Checks if the first string is a substring of the second one.
- Returns 0 if it is not a substring / 1 if it is / -1 if it is a “circular substring”
this is an example of what it should do

- abcde is a substring of blkjabcdelkjsd  return 1
- abcde is not a substring of slfkjsdlskggfhjkh  return 0
- abcde is a “circular substring” of delkjlkjabc  return -1

Can Anyone help?

All I have is

public static int substring(String Str1, String Str2)
 {
   index1 = Str2.indexOf(Str1) 
 
 if (index1 >= 0)
 {
  return 1;
 else
 
 }

Here's a simple algorithm to check if a substring is contained within another string:

1. start from the beginning of the larger string
2. If the remaining characters is greater than the length of the second string, do 2a. Otherwise, do 2b
2a. Use the substring() method of the String class to take a chunk that has the same length as the smaller string
2b. Use the substring() method to take the rest of the letters in the larger string, then add on the remaining characters needed from the beginning
3. compare if they are equal using the equals() method. If they are equal, return 1 or -1, depending on whether you used 2a or 2b. Otherwise, repeat 2-3 up to the last character in the larger string
4. If you still haven't found a substring match, return 0.

public static int substring(String Str1, String Str2)
 {
 int return = 0 
 for(int i = 0; i < Str2.length(); i++)
 {
   if (Str2.charAt(i) == Str1.charAt(0))
           for(int j =0; j < Str2.length(); j++) 
              {
           if (Str2.charAt(i) == Str1.charAt(j))
 
             return = 1;
           else 
             return = 0;
   }
 }
 for(int i = 0; i < Str2.length(); i++)
 {
   if (i = Str2.length())
       i = 0
     for (int j = 0; j < Str2.length(); j++)
 
     return -1;
 }
}
}

this is the code that I came up with for this problem can anyone see any errors with it
if so please help me out in pinpointing them out

You're return statements are pre-mature. The program hasn't completely checked that the string is contained str2 is a substring of str1, but you're saying it is. Also, return is a Java keyword. You can't declare variables called return. There are a few other Java syntax errors (missing semi-colons).

public static int substring(String str1, String str2)
{
     for (int i = 0; i+str2.length() < str1.length(); i++)
     {
          if (str2.equals(str1.substring(i,i+str2.length()))
          {
               return 1;
          }
     }
     for (int i = str1.length()-str2.length(); i< str1.length(; i++)
     {
          if (str2.equals(str1.substring(i,str1.length)+str1.substring(0,str2.length-i)))
          {
               return -1;
          }
     }
     return 0;
}

Give this a go.

you're missing a closing parenthesis

str2.equals(str1.substring(i, str1.length()[b])[/b] + str1.substring(0, str2.length() - i)))

subVirus? I merged your two topics and marked the original one as un-solved.

Oops, made a few logical errors in my solution a few posts back.

	public static int substring(String str1, String str2)
	{
		if (str2.length() > str1.length())
		{
			return 0;
		}
		for (int i = 0; i + str2.length() <= str1.length(); i++)
		{
			if (str2.equals(str1.substring(i, i + str2.length())))
			{
				return 1;
			}
		}
		for (int i = str1.length() - str2.length() + 1; i < str1.length(); i++)
		{
			if (str2.equals(str1.substring(i, str1.length()) + str1.substring(
					0, i - str2.length() + str1.length())))
			{
				return -1;
			}
		}
		return 0;
	}