how to make custom loop in C?

[oldboy]

Yes i know, my question is not very clear but let me explain what i want to do.

I want to make a loop in a program that will have specific amplitude and the counter will take all the possible values of this amplitude.
For example in a for loop we have:

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for(i=0;i<N;i++){
     ...//code
}


At this for loop the counter i takes the values from 0...N-1.

At my custom loop, i want to give the start point for the counter i but after that will take all the values to N-1 plus the values before tha start point.
Example: For N=6 if counter i starts from 4, it will take the values: i=4,i=5,i=6,i=0,i=1,i=2,i=3 (a complete loop for N=6).

thanks

**update: not necessery to be for loop, i am interested for the behavior of i counter.

[Alvaro]

Several options:

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for (int i=0; i<6; ++i) {
  int shifted_i = (i+4)%6;
  // do stuff with shifted_i
}

or you can save yourself the somewhat-expensive modulus operation, doing something like this:

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for (int i=0, shifted_i=4; i<6; ++i, (++shifted_i==6)&&(shifted_i=0)) {
  // do stuff with shifted_i
}

or, if you put your code in a function, you can use the following less-messy option.

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for (int i=4; i<6; ++i)
  do_something(i);
for (int i=0; i<4; ++i)
  do_something(i);

[oldboy]

god damn it man... What are you made off? Is there something that you don't know how to do it?

I was just ready to post a try with

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i=(i+1)%N

but i am not sure if it works.

Thanks, i will make some tries with your options in my code.

[Alvaro]

:o god damn it man... What are you made off? Is there something that you don't know how to do it?

Oh, there probably is something. Keep trying me.

I was just ready to post a try with

Code: Select all

i=(i+1)%N

but i am not sure if it works.

You can make that work, for instance like this:

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int i=4;
do {
  // your code here
  i=(i+1)%6;
} while(i!=4);

In the end, use the option that you find easiest to understand. The most important property code should have is clarity.