Validate Data

[Sally]

What expression should I use to validate data ---
This passes:
1
34
1.0
34.
..5

This fails:
1,0 'comma
1.o 'o not zero
4 .0 'space after 4
2. 5 'space before 5

Thanks

Sally

 

[John Vinson]

What expression should I use to validate data ---
This passes:
1
34
1.0
34.
.5

This fails:
1,0 'comma
1.o 'o not zero
4 .0 'space after 4
2. 5 'space before 5

Given that Europeans often use , as a decimal separator, 1,0 is
actually a valid number; if you're putting it into a Number field it
will become 1.0.

But to answer the question as posted:

IsNumeric([fieldname]) AND NOT LIKE "*,*"