Question

I am a real newbie regarding Regular Expressions (RegEx)

I am looking for a RegEx1 to only match strings containing no spaces.
RegEx2 to only match strings containing spaces.

Example:

RegEx1 must match "abcxyz" but NOT "abc xyz".
RegEx2 must match "abc xyz" but NOT "abcxyz".

Answer 1

You want to learn about character classes:

[abc] matches a character that is either an a, a b or a c.

[^abc] matches any character that is neither an a, a b nor a c.

Together with quantifiers and start- and end-of-string anchors, you’re all set.

^[^X]*$ matches a string of any length that doesn’t contain X.

^.*X.*$ matches any string that contains at least one X.

^[^X]*X[^X]*$ matches a string of any length that contains exactly one X.