I have a design

while (true) {
  for (;;) {}
}

How do I get out of the infinite WHILE cycle inside the FOR cycle?

Answer 1, Authority 100%

Unfortunately, unlike Java, C and C++ do not support the mechanism like BREAK LABEL , so the cleanest option is to use Goto:

int main () {
  While (True) {
    for (;) {
      Goto Breakall;
    }
  }
Breakall:
  Puts ("I'm Out!");
}

You can also use the flag:

int main () {
  BOOL RUNNING = TRUE; // BOOL is defined in stdbool.h
  While (Running) {
    for (;) {
      Running = False;
      Break;
    }
  }
  Puts ("I'm Out!");
}

Large difference between these options is not.

In addition to this case, Goto is also used in a good C for error handling:

bars_t foo () {
  BAR_T * BAR1 = Malloc (SizeOF (* Bar1));
  If (! Bar1) {
    Goto CleanUnothing;
  }
  BAR_T * BAR2 = Malloc (SizeOf (* Bar2));
  If (! Bar2) {
    Goto CleanupBar1;
  }
  // ...
  Return (Bars_T) {
    .one = bar1,
    .two = BAR2.
  };
// in the reverse order of definition
CleanupBar2:
  FREE (BAR2);
CleanupBar1:
  FREE (BAR1);
CleanUnothing:
  RETURN (BARS_T) {0};
}

in C++ this is not necessary, because There is Raii, but from cycles still go through Goto .

Answer 2, Authority 71%

I will add a couple of ways.

The specified code is submitted to a separate function. And now you can go on the usual Return .

Method two – you need to create a variable flag. And check it. Somewhere so

bool go = true;
While (GO) {
  for (;;) {if (...) {go = false; Break;}
}

But this is a bad way.

Answer 3

try
{
  While (True)
  {
    for (;;) {throw 1; }
  }
}
Catch (int)
{
  // came out of two eternal cycles at the same time
}

Answer 4

{
While (1)
 {
 for (;;)
  {
  if (...)
   Goto Away;
  }
 }
Away:;
}

Answer 5

inline bool func () {
  BOOL EXIT, ONLY_BREAK;
  for (;) {
    if (exit) {
      Return 1;
    }
    if (only_break) {
      Break;
    }
  }
  Return 0;
  }
  INT MAIN () {
  While (1) {
    if (FUNC ()) {
      Break;
    }
  }
}