Which function is commonly used to extract a portion of a string by specifying a starting position and length?

Which function is commonly used to extract a portion of a string by specifying a starting position and length?

• A. Upper
• B. Substring
• C. Left
• D. Right

Answer: (B)

Extracting a portion of a string by giving a starting position and a length is done with a substring operation. The function named Substring is designed to return exactly that slice: it takes the original string, a starting index, and a length, and outputs the characters in that range. For example, many languages or SQL dialects use something like substring('abcdef', 2, 3) to yield 'bcd' (depending on indexing rules). This is what makes it the best fit here. The other options don’t fit the same pattern. Upper changes every character to uppercase, not a slice of the string. Left takes characters from the left end of the string only, while Right takes from the right end, both without specifying an arbitrary middle start. If you need a portion from anywhere inside the string with a chosen length, Substring is the appropriate choice.

Extracting a portion of a string by giving a starting position and a length is done with a substring operation. The function named Substring is designed to return exactly that slice: it takes the original string, a starting index, and a length, and outputs the characters in that range. For example, many languages or SQL dialects use something like substring('abcdef', 2, 3) to yield 'bcd' (depending on indexing rules). This is what makes it the best fit here.

The other options don’t fit the same pattern. Upper changes every character to uppercase, not a slice of the string. Left takes characters from the left end of the string only, while Right takes from the right end, both without specifying an arbitrary middle start. If you need a portion from anywhere inside the string with a chosen length, Substring is the appropriate choice.