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Array lookup

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Someone told me that array lookup is slow (I guess compared to accessing a normal variable). Is this true? And if so, why? I''d like to know the details about when it''s slower and when it isn''t. For example, is it always slower? Or is it only slower when you index the array with a value known only at run-time? I''d like to know the order these finish in terms of speed. 1. Array lookup by a variable index. n = array; // where i is unknown at compile time 2. Array lookup by a constant variable. #define START 0 n = array[START]; 3. Array lookup by a constant index on a global array. This would seem to be faster since the compiler knows the address of the global array AND the index at compile time, so it should be able to get the addresses of those at compile time. Thanks, Russell

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