This is something to skim and spot bits you didn’t know, leading you to the relevant bit of the fine manual. It has errors though, e.g. /\<\d\d\d\d\> : S

This is something to skim and spot bits you didn’t know, leading you to the relevant bit of the fine manual. It has errors though, e.g. /\<\d\d\d\d\> : Search for exactly 4 digit numbers /\D\d\d\d\d\D : Search for exactly 4 digit numbers /\<\d\{4}\> : same thing The middle one is not the same as the other two since \D has to match something unlike the zero-width assertions of \< and \> for beginning and end of word.