Question

What is the return value of "select".substring(4, 4)?

Answer 1

The expression "select".substring(4, 4) will return an empty string, as the start and end indices are the same and no characters are included in the specified range.

Step-by-step explanation:

The substring method in many programming languages, including Java and JavaScript, is used to extract a portion of a string between two specified indices. In the expression "select".substring(4, 4), we are asking for the part of the string starting at index 4 and up to, but not including, index 4. Since the start and end indices are the same, the method will return an empty string.

It's important to note that string indices are zero-based, meaning that the first character of the string is at index 0. The string "select" has six characters, with indices ranging from 0 to 5. Therefore, calling substring with identical start and end indices will not include any characters in the resulting string.

Example:

• To retrieve the first character of "select", you would use "select".substring(0, 1).
• To retrieve "lec" from "select", you would use "select".substring(1, 4).

Answer 2

I'm assuming the syntax here is Javascript:

The str.substring() method takes in two integers - a start index and an end index - and returns all the characters in the specified range from the original string, including the character in the start index and excluding the character in the end index. Javascript's is 0-indexed, which means that all of its indices start at 0.

For instance, if we were to use the method on the string "test" and wanted to return the substring "tes", we'd call the following method:

"test".substring(0,3)

This would return everything from the first character, "t", up to but not including the fourth character, "t". The character immediately before the last "t" (index 3), "s" (index 2) would be our last character, and the console should print "tes" as a result.

For your example, "select".substring(4,4) prints out every character starting at index 4 - the fifth character, "c" - up to but not including the character at index 4. We start and stop at the same character, so the method will only return the character "c", and nothing else.