Compiler Error?
Gertjan van Oosten
gjoost at westc.UUCP
Thu Feb 16 21:30:13 AEST 1989
In article <683 at sbsvax.UUCP> greim at sbsvax.UUCP (Michael Greim) writes:
>Consider the following program:
...
> (j = 2) ? k = 3 : 4;
...
>On 43BSD, SunOS 3.4, ULTRIX 2.0 this compiles with no error.
>
>According to the C books I could get my hands on,
>"?:" has higher precedence than the assignment operators, like
>"=" for instance. (In X3J11 too)
Your quote from the C-books is right, but you should read it more
carefully:
"?:" has higher precedence than assignment.
^
+--- spot the colon there!
So this means, that an expression like:
a = b ? c : d
is parsed as:
a = (b ? (c) : d)
"?:" is a ternary operator, with operands b, c and d (assuming that
b and d don't contain unparenthesised expressions containing lower
precedence operators).
>Thus the compiler should find an error in the statement, something
>like "misplaced assignment".
No, it shouldn't.
>SIEMENS SINIX v2.1 finds an error.
Siemens SINIX v2.1 is an error. :-)
Yours sincerely,
G. J. van Oosten.
"Peace on earth and mercy mild, Mother Brown has lost her child.
Just another forgotten son....."
Marillion, "Forgotten Sons"
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