Date: 2010may3 Language: C/C++ Keywords: no-op Q. How can I do an assembler-like NOOP in C/C++ ? A. If you really want to do nothing you can do:

#define NOOP /* do nothing */ ExampleUse() { NOOP }

or

// Notice there is no trailing semicolon #define NOOP_FUNCTION do { /* do nothing */ } while (false) ExampleUse() { NOOP_FUNCTION(); // This might not get compiled down to nothing }

or

inline void Noop() { /* do nothing */ } ExampleUse() { Noop(); }

or

In some environments, in <stdarg.h> you have:

#define va_end(ap) ((void)0) which does very little. ExampleUse() { va_end(ap); }

But sometimes you want a very small time delay. So you can try:

true; ExampleUse() { true; // Very small delay }

In Windows you can do:

Sleep(0);

Which appears to do very little. It will sleep zero milliseconds and but also give control to another process if it is waiting.