I get a warning saying: Use of logical "||" with constant operand. And it doesn't work the way I intend.Code:if ( opcode == (0x0) || (0x1)|| (0x2) || (0x4)|| (0x6)|| (0x1)) { //blah }
Is there a proper syntax for this kind of operation? I just want to see if the variable "opcode" is equivalent to either one of the hexadecimals on the right.
Thanks
This really should go into the "Frequently Asked Rank Beginner Question" list.
The proper syntax for "this type of operation" is
Code:if (opcode == 0x0 || opcode == 0x1 || opcode == 0x2 || opcode == 0x4 || opcode == 0x6 || opcode == 0x1) { // blah }
yeah i just tried that. thanks.
IMO, a switch-case construct is better in this situation to make the code more compact and legible.
So nobody else noticed the 0x01 repeated?
FYI, there is an old trick that allows you to check for equality against a bunch of possible values from 0 to 31 all in one hit. It goes like this:And of course it doesn't look that pretty, but it can be tidied up by writing a bunch of macros for it.Code:if (opcode < 32 && ((1 << opcode) & ((1<<0) | (1<<1) | (1<<2) | (1<<4) | (1<<6))) != 0) { // blah }
But yeah this is not something you want to use before you understand it, and is premature optimisation here anyway.
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Yeah, I noticed it, but I left it in my response anyway. For all I knew, opcode was a volatile variableOriginally Posted by iMalc
