How to use lookahead and $ with regex?

@tressie.damore 

Lookahead in regex allows you to match a pattern only if it is followed by another specific pattern. The syntax for lookahead in regex is (?=...), where ... is the pattern you want to match.

For example, if you want to match the word "hello" only if it is followed by the word "world", you can use the following regex pattern:

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hello(?=world)

In this pattern, hello will only be matched if it is immediately followed by world.

The $ symbol in regex is used to match the end of a line or the end of a string. If you want to match a pattern only if it occurs at the end of a string, you can use the $ symbol at the end of your regex pattern.

For example, if you want to match a string that ends with the word "world", you can use the following regex pattern:

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world$

This pattern will only match the word "world" if it appears at the end of the string.

You can also combine lookahead and the $ symbol in regex to create more complex matching patterns. For example, if you want to match the word "hello" only if it is followed by the word "world" and occurs at the end of a string, you can use the following regex pattern:

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hello(?=world)$

In this pattern, hello will only be matched if it is immediately followed by world and occurs at the end of the string.

Overall, lookahead and the $ symbol in regex can be powerful tools for creating more specific and complex matching patterns.