Q65645: Use of Ternary Conditional Operator with a Constant

Article: Q65645
Product(s): See article
Version(s): 6.00   | 6.00
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | buglist6.00 | mspl13_c
Last Modified: 24-OCT-1990

The following use of the ternary conditional operator (?) should
convert the integer 2 into a float to match the 3.00. However, because
the constant 1 is used instead of a variable, the conversion is never
done. Instead of 2.0 (float), 2 (integer) is passed to printf() and
instead of printing 2.000000, the program prints 0.000000.

Sample Code
-----------

#include <stdio.h>

double x;

void main (void)
{
   x= 5.5;
   printf ("%f\n", 1?2:3.00);
}

According to the ANSI Standard, if the second and third operands to a
conditional operator are arithmetic types, the usual arithmetic
conversions are performed to make them a common type. (See Section
3.3.15, Lines 6-10). In this case, they should both evaluate to
floats.

Microsoft has confirmed this to be a problem in C version 6.00. We are
researching this problem and will post new information here as it
becomes available.

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