Zero-choice alternative
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If action is volatile, it would be possible for the second test to succeed even if the first fails. Indeed, if it's a memory-mapped mapped register, such behavior might even be expected.
Reminds me of that little DOS / Win console classic to wait for a keystroke:
if (!getch()) getch();:cool: yes, this is the right way to do it -
Wouldn't float.IsNaN(x) be a more readable way to achieve that?
Only decimal numbers have NaN as static class member (at least ni C#), natural numbers like int or short don't have it. Though if something is NaN, you would get an error the moment it's assigned to a natural number variable.
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If "foo" is volatile, the statement "if (foo == foo) bar();" must read the value of foo exactly twice and compare the two values read. If "foo" happens to be an address in normal RAM, the two reads would be most likely read the same data unless an interrupt or task switch happened to occur between them (not terribly likely). Not everything in a processor-based system is RAM, however. When a typical flash memory chip is performing a write cycle, consecutive read operations are guaranteed to return different data. If the generated code for the above 'if' statement didn't read 'foo' twice, the 'if' test would succeed even while the flash was still being written.
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hey, if would b gr8 if u could explain wat u mean by variable being volatile
Ravie Busie Coding is my birth-right and bugs are part of feature my code has!
hey, if would b gr8 if u could explain wat u mean by variable being volatile This is not a place for programming questions, but in this context, a 'volatile' variable is one that is marked with the 'volatile' keyword. If a variable is declared volatile, expressions involving that variable may not be optimized. If 'foo' were not volatile, the code (assume foo, bar1, bar2, and bar3 are of type int):
foo = bar1;
bar2 = foo*25;
bar3 = foo*25;
foo = 8;could be safely replaced with:
bar3 = bar2 = bar1 * 25;
foo = 8;and indeed some compilers would make such a replacement. If 'foo' were volatile, however, all four of the original statements would have to be performed as-is, in sequence.