Sometimes, if you have large arrays, it is better to not use '''[foreach]''' and '''[array] get''' to loop through an array, as it creates a list copy of your array with a quite hefty memory cost:
 foreach {key value} [array get arrName] {#do something with key and value}

Another alternative is
 foreach key [array names arrName]] { #get current value with $arrName($key) }

 foreach key [lsort -dictionary [array names foo]] { ... }

Better do it like this, using '''[while]''' and the '''[array]''' search facilities. (Those are a direct mapping of the C level functionality for a Tcl_HashTable ).


 set searchToken [array startsearch largeArray]
 while {[array anymore largeArray $searchToken]} {
     set key [array nextelement largeArray $searchToken]
     set value $largeArray($key)
     
     # do something with key/value

 }
 array donesearch largeArray $searchToken

Question: how big does an array need to be to make this the better approach?