[Tutor] What is a semantic error?

[Richard D. Moores]

Here are 3 examples of syntax errors:

>>> print('and)
Traceback (most recent call last):
  File "<string>", line 1, in <fragment>
Syntax Error: print('and): <string>, line 112
>>> if 3 > 2
...   print(3)
...
Traceback (most recent call last):
  File "<string>", line 1, in <fragment>
Syntax Error: if 3 > 2: <string>, line 19
>>> if 34 345:
...    print(34)
...
Traceback (most recent call last):
  File "<string>", line 1, in <fragment>
Syntax Error: if 34 345:: <string>, line 19
>>>

But could someone give me a clearcut example of a semantic error? And
a definition that delineates semantic errors from syntax errors.

I googled this one up,
http://ubuntuforums.org/showthread.php?t=527855, where the guy uses
'&' where he should have used 'and'. That's clearcut, but is it really
a semantic error? If he had used, say, '!' where he used '&' (which it
seems has meaning in that context), that would be a syntax error,
right?

>>> if 3 == 3 & 4 > 3:
...   print("Duh")
...
>>>

>>> if 3 == 3 ! 4 > 3:
...    print("Doh!")
...
Traceback (most recent call last):
  File "<string>", line 1, in <fragment>
Syntax Error: if 3 == 3 ! 4 > 3:: <string>, line 111
>>>

Is a semantic error one that Python doesn't see as an error -- no
error is raised; whereas syntax errors aren't errors unless Python
sees them as "Syntax Error"s?

Thanks,

Dick Moores