FOR Command

Material prepared from M Programming Book (Page 108) [WALTERS1997] and GT.M Programmer’s Guide

Command

F[OR] [variable=start[:increment[:limit]]][,...]

Description

FOR will repeat the remaining commands on the line, incrementing variable by increment until

  • variable would be greater than limit if increment is non-negative.
  • variable would be less than limit if increment is negative.

This means that FOR I=10:-1:1 WRITE I,! will print the numbers from 10 to 1 in descending order as expected. variable will not be beyond limit after the loop exits.

Omitting limit will cause the loop to continue endlessly unless a command inside the loop causes it to end (e.g. QUIT).

Block Structuring

FOR can loop over more than the remainder of the line by using DO or XECUTE. Additional lines are indented with a period and a space.

Examples

FOR I=1:1:10 WRITE I,!

FOR I=1:1 DO  QUIT:I>7
. WRITE " I= ",I
. WRITE " I Square= ",I*I,!

Notice that there are two spaces between DO and QUIT.