bash - how to check if string starts with specific prefix

Let's assume we want to process only files that start with specific string (eg. 2018). Our script is listening to every new file appeared in given directory, so let's assume we cannot do this at the os level directly. Our script is invoking the following command:

$ convert.sh /path/to/2018_file.pdf 

To process all files begins with 2018 we can do this way:

for i in `ls`; do [[ $i == 2018* ]] && echo $i; done

Or, if we'd like to process all but 2018 files we can do this way:

for i in `ls`; do [[ $i != 2018* ]] && echo $i; done

Or even more general with help of regexp we can do

for i in `ls`; do [[ $i =~ ^2018 ]] && echo $i; done

Happy New Year!!