Loop Imitations

Hi!

As some of you may know, I'm currently learning C++ and would like to know something; I know that many of the loops in C/C++ can be represented using a regular while loop. In the following examples, please correct me if I'm wrong:

Representing a while-statement using a do-statement

Code:

---

do
{
    if (/* condition */)
    {
          // ...
    }
    else
          break;
} while (true);

---

Representing a for-statement using a do-statement

Code:

---

int i = 0;
do
{
    if (i < MAX)
    {
          // ...
          i++;
    }
    else
          break;
} while (true);

---

Representing a while-statement using a for-statement

Code:

---

for (; /* condition */;)
{
    // ...
}

---

Representing a do-statement using a for-statement

Code:

---

// the statements go here...
for (; /* condition */;)
{
    // same statements as above...
}

---

These are my guesses at the moment. Please feel free to correct me if I happened to make a mistake in any of those or if you see that any of them are inefficient (say, if I included something that was not necessary and there is a better way to represent the same thing, etc.)

Thanks!

Of course, any of these loops can be done using just 'if' and 'goto'. We have all these different loop structures because it makes it a little bit easier on the programmer

I think the most common loop that I use is

Code:

---

while(true){
  ...break;
}

---

and

Code:

---

for(unsigned int = 0; i < whatever; i++){

}

---

I really don't think there is a difference in performance, I think by the time they hit the abstract parse tree, they are the same. The only limitation that I can think of is that for loops and such are limited by the type that you use as the iterator.

Quote:

---

Originally Posted by EsX_Raptor

Representing a do-statement using a for-statement

Code:

---

// the statements go here...
for (; /* condition */;)
{
    // same statements as above...
}

---

---

This way you have to write the same code twice. You can also write a do-loop as a for-loop and keep the body the same.

Quote:

---

Originally Posted by ninja9578

I think the most common loop that I use is

Code:

---

while(true){
  ...break;
}

---

and

Code:

---

for(unsigned int = 0; i < whatever; i++){

}

---

I really don't think there is a difference in performance, I think by the time they hit the abstract parse tree, they are the same. The only limitation that I can think of is that for loops and such are limited by the type that you use as the iterator.

---

while(true) isn't a really good habit to get into. It's better practice to put a condition in the while statement rather than rely on a break somewhere in the body.

I know, I do that whenever I can, but I've found myself recently having multiple situations that can break the loop, or I have code that has to be placed at the end of the loop that I don't want to run. Don't worry, I stress test it and make sure that there is no way for it to run infinately.

Quote:

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Originally Posted by GCDEF

while(true) isn't a really good habit to get into. It's better practice to put a condition in the while statement rather than rely on a break somewhere in the body.

---

Generally, I agree (though I prefer for (;;) ;)), but in some cases such a refactoring (particularly to convert to a do while loop) requires pulling out code into a function, which may be overkill.