Question on for loop.

[coffytan]

Dear,
Recently I found an example program from the net. There's 1 line of statement it specified like this: for(;.
When I compile, the compilation is successful. Anybody can tell me what are this for loop doing??
Thank you in advance.


Best regards,

Coffy Tan

 

[chipperMDW]

There is no initialization statement, therefore nothing happens in the initialization step before starting the loop.

There is no stop condition, so the loop continues until a break or return is encountered, or an exception is thrown (or a longjmp, or a goto outside the loop, or... ).

There is no update statement, so nothing is done between each iteration of the loop.


A faster and easier way to get an answer to this question would be to try it and find out yourself.

 

[ArkM]

Some addition (syntax & pragmatics:
any clause of for(prelude;condition;interlude) may be empty.
This 'degenerated' form may be useful in a program case like:

for (;;)
{
  do non-trivial calculations (or some test case);
  make decision if you may (must) continue or must break;
  do some works (with previous result or what else);
  // and try again
}

The 2nd program case: main loop of non-stop service (until a server die)...

 

[coffytan]

Thx for your information.

 

[xwb]

It is the efficient alternative to

while (1)
{
...
}

or

do {
...
} while (1);

Why efficient? No comparison is done. You can always compare the code generation. Some optimizing compilers will generate the same code on all three.