# Thread: Random char Array

1. ## Random char Array

Dear all,

i want to randomize the numbers of a char array, like:

if a have a number 1234. With the function itoa i will have an array like this:
a[0] = 1;
a[1] = 2;
a[2] = 3;
a[3] = 4;

This work fine. Now i want to generate ALL new integers which are made of these values:

1234, 1243, 1324, 1342, 1423, 1432
2134, 2143, 2314, 2341, 2413, 2431
3124, 3142, 3214, 3241, 3412, 3421
4123, 3132, 4213, 4231, 4312, 4321

Do you have an idea how to do this?

Regards

2. I have some ideas, but I REALLY want to see what solution you were thinking about; some pseudo-code will be fine.

3. if i think in the way as i as a human did:

1. start with low to hight (element1-element2-element3-element4)

2. element 1 & element 2 stays the same, interchange element 3 & element 4

3. element 1 & element 3, put element 3 & element 4

4. element 1 & element 3, interchange element 3 & element 4

5. element 1 & element 4, put element 3 and element 4

6. element 1 & element 4, interchange element 3 & element 4

7. element 2 & element 1, put element 3 & element 4

8. element 2 & element 1, interchange 3 & element 4

9. element 2 & element 3, put element 1 & element 4

10. element 2 & element 3, interchange 1 & element 4

11. element 2 & element 4, put element 1 & element 3

12. element 2 & element 4, interchange 1 & element 3

and keep going like this

4. So you have a set of 4 elements (1, 2, 3, 4) and you need to find all of it's permutations?

Have fun googling "c permutations".

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