Multi-statement Macros in C++

Question

In C++, is it possible to make a multi-statement macro with nested if statements inside of it like the one below? I\'ve be

Answer 1

Note that some of the answers here have a problem.

For example, for a normal statement you can do this:

if (foo)
   function();
else
   otherstuff();

If you followed some of the suggestions here, but if replace function with a macro, it might expand to:

if (foo)
   if (something) { /* ... */ }
   else           { /* ... */ }; // <-- note evil semicolon!
else
   otherstuff();

So a common (ugly) hack that people do to avoid this is:

#define MATCH_SYMBOL(symbol, token)    \
    do                                 \
    {                                  \
       if(something == symbol)         \
       {                               \
          if( symbol == '-')           \
          {                            \
          }                            \
          else if (symbol != '-')      \
          {                            \
          }                            \
          other steps;                 \
       }                               \
    }                                  \
    while (0) // no semicolon here

This is so that the "statement" MATCH_SYMBOL(a, b) can end with a semicolon just like a normal statement. You also have braces around the multiple statements.

If you think nobody's crazy enough to use this technique, think again. It's very common in the Linux kernel, for example.