Can I use 2 loop statement in one loop?

Question

is this loop statement is correct? if not correct then what alternative way? I am trying to o(n) loop statement like this-

for(int i=0 ; i<n  ; i++ , j=n ; j<n*2 ; j++){
    continue;
  }

Answer 1

What you seem to want is something like:

for (int i = 0, j = n; i < n && j < n * 2; ++i, ++j)
{
    continue;
}

---

To help you better understand what I did and why, and how you can do such transformations in the future, you need to understand how a for loop is really handled by the compiler: As a special while loop.

For example, if you have

for (a; b; c)
{
    d;
}

then that's equivalent to this:

{
    a;
    while (b)
    {
        d;
        c;
    }
}

If we take what you (probably) want, in the form of a while loop then it would be

{
    int i = 0, j = n;  // a in my example above
    while (i < n && j < n * 2)  // b in my example above
    {
        continue;  // d in my example above
        ++i, ++j;  // c in my example above
    }
}

Now it's easy to translate it to the for loop I showed initially.

As noted in a comment, the while loop shown here is a little misleading, as it won't actually do the increment. But then I assume your real loop doesn't have an unconditional continue statement as the only statement in the body. That would make the loop rather meaningless. However the principle is still valid, even if the example isn't.

Answer 2

The construct is wrong, you cannot you two loops in one construct, but you can have more than one variable controlling the iteration.

For example, you can have

• Two (or more) variables, i and j , initialized with certain values.
• A loop controlling statement, involving operation and condition check on i and j (and others, if defined).
• Finally, you can control the increment or decrement of i and j (and others, if defined).

A sample construct can be:

 for (int i = 0, j = n; i < n && j < n * 2; ++i, ++j)
                                            |^^^^^^^| -------- variable modification
      |               |   |^^^^^^^^^^^^^^^^^| ---------------- loop condition
      |^^^^^^^^^^^^^^^|--------------------------------------- initialization

Answer 3

if you want to run the loop only if two of them are true then use && between the two conditions eg: for(int i=0 ; i<n ; i++ && j=n ; j<n*2 ; j++) { continue; } for(int i=0 ; i<n ; i++ && j=n ; j<n*2 ; j++) { continue; }

or if you want to run the loop only if anyone of them become true use || between the two conditions eg: for(int i=0 ; i<n ; i++ || j=n ; j<n*2 ; j++) { continue; } for(int i=0 ; i<n ; i++ || j=n ; j<n*2 ; j++) { continue; }

ie, && stands for logical AND || stands for logical OR

Answer 4

for(int i=0 ; i<n  ; i++ , j=n ; j<n*2 ; j++){
    continue;
  }

The above code is wrong but it can be written as

for(int i = 0 ,j = n; i < n ,j < n * 2; i++ ,j++)

The above code is correct i=0 and j=n is initialization i<n and j<n*2 is loop condition i++ and j++ is incrementation