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loop command
For I := N_1 To N_2 Do C EndFor
For I := N_1 To N_2 Step D Do C EndFor
where I is a dummy variable, N_1, N_2, and D are integer expressions,
and C is a sequence of commands.

In the first form, the variable I is assigned the values
N_1, N_1+1, ...,N_2
in succession. After each assignment, the command sequence C
is executed. The second form is the same, except that I is assigned
the values
N_1, N_1+D, N_1+2D, etc. until the greatest value less than
or equal to
N_2 is reached. If
N_2 < N_1, then C is not executed.
Note: Large values for
N_1, N_2, or D are not permitted; typically
they should lie in the range about
10^9 to
+10^9.
Note: Don't forget the capitalization in the word
To.
For N := 1 To 5 Do Print 2^N, " "; EndFor;
2 4 8 16 32

For N := 1 To 20 Step 3 Do Print N, " "; EndFor;
1 4 7 10 13 16 19

For N := 10 To 1 Step 2 Do Print N, " "; EndFor;
10 8 6 4 2

For N := 5 To 3 Do Print N, " "; EndFor;  no output

Loops can be nested.
Define Sort(Var(L))
For I := 1 To Len(L)1 Do
M := I;
For J := I+1 To Len(L) Do
If L[J] < L[M] Then M := J EndIf;
EndFor;
If M <> I Then
C := L[M];
L[M] := L[I];
L[I] := C
EndIf;
EndFor;
EndDefine;
M := [5,3,1,4,2];
Sort(M);
M;
[1, 2, 3, 4, 5]


(Note that
Var(L) is used so that the function can change the value
of the variable referenced by L. See
Var.)