Structured Programming

The flow of processing by QCL when reading commands from an command file can be controlled using the following.

.BEGIN
.UNTIL <logical expression>

.IF <logical expression>
.ELSEIF <logical expression>
.ELSE
.ENDIF 

.DO <name>=<start>,<end>,<step>
.LOOP 
.EXIT 
.QUIT

The commands .ENDIF and .ELSEIF must be typed as one word without spaces or tabs. <name> in the .DO command is the name of the loop variable. Note that the <start>, <end>, <step> parameters of the .DO structure can be expressions and if <step> is ommitted then step=1 is taken as the default. If <end> is already out of range when the structure is entered the loop is missed completely. All structures must be resolved within each command file and they can all be nested as required.

The command .EXIT will terminate QCL and save all the current assignments on a file. These assignments will automatically be picked up again when QCL is re-started even if you have logged-off the machine in the mean time. The command .QUIT will also terminate QCL but without saving the current assignments. This is the quickest way of leaving QCL. Note that <ctrl> d in reply to the qcl> prompt has the same effect as the .EXIT command.