Regular expression for one character only

Question

I need a regular expression for a string with exactly one alphabetic character in it.

For example, it should match:

• 8*x=16
• x+2=2
• u329398239823
• 43044343k43304403

...but not:

• xsfdjfefljefe
• 44434f9434343 f
• 98(***(*)))(*)(0((-900-87
• 32233232

Answer 1

/^[^a-z]*([a-z])[^a-z]*$/i

i for case-insensitive matching.

^ and $ anchors to force the regex to match the entire string.

( ) to capture the letter.