### Thread: sortalgorithm of more than one column

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#### sortalgorithm of more than one column

Hi,
i search a possibility to sort an array with more than one key (like an ORDER BY X, Y in SQL). I have searched the whole internet after this information, but without any help ...

I have a random-file, with more than 200.000 records. The quicksort-routine for one key is very fast and no problem. But i need more: I have 3 values

ID,LAT,LONG

And now i want to sort the LAT AND!!! the LONG values tougether, because some LAT values are equal.

Hope i found here a answer of my question ... and a solution of my project (which is stopped since over a week, due this problem )

Thanks,
Richard
2. #### different sort

U have to make a first sort on the first key, then u have to make a second sort on every subgroups generate with the second key and so on...
An example:
the initial matrix
B 3 c
C 2 c
A 1 b
A 3 a
C 1 b
C 3 a
B 1 a
B 2 b

the matrix after the first sort using the first key
A 1 b
A 3 a
B 3 c
B 1 a
B 2 b
C 2 c
C 1 b
C 3 a

the matrix after the second sort using the second key
A 1 b
A 3 a
B 1 a
B 2 b
B 3 c
C 1 b
C 2 c
C 3 a

the final matrix after the third sort using the third key
A 3 a
A 1 b
B 1 a
B 2 b
B 3 c
C 3 a
C 1 b
C 2 c

I hope that now u can restart to coding