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#!N 
#!CNavyBlue #!N 
 #!Rloop Iteration using Looping #!N #!EC #!N #!N The sequencer provides 
a basic loop; however it has some limitations. Only one sequencer 
per visual program is allowed, and, as it executes, everything in 
the visual program executes (subject to the optimization for deciding which 
modules need to be executed, discussed above). Additional functionality is provided 
using the ForEachN, ForEachMember, Done, and First modules. #!N #!N ForEachN 
and ForEachMember essentially implement a standard programming-language "for" loop; in the 
case of ForEachN iterating over a specified list of integers, and 
in the case of ForEachMember iterating over the members in a 
group or the items in a list (or array).  #!Lxmodx440,dxall268 f Figure 40  #!EL  shows 
a simple loop that outputs the integers 0 to 10 and 
Echo's them (the  #!F-adobe-times-bold-r-normal--18*   start #!EF and  #!F-adobe-times-bold-r-normal--18*   end #!EF parameters 
to ForEachN have been set to 0 and 10 respectively). This 
is roughly equivalent to the C-language statements #!CForestGreen #!N #!N  #!F-adobe-courier-bold-r-normal--18*   
#!N for (i=0; i<=10; i++) #!N printf("%d", i); #!EF #!N #!N 
#!EC #!Cbrown #!N  #!F-adobe-times-medium-r-normal--18*    #!Rxmodx440 #!N Graphics omitted from Online Documentation. 
Please see the manual. #!N #!N Figure 40. Example 4 #!EF 
#!N #!EC #!N #!N Data Explorer provides you with two other 
tools for control looping, Done and First. Done enables you to 
exit a loop. Examples of its use can be found in 
"Advanced Loop Constructs" (see below). The First module provides a way 
to recognize the first pass through a loop; this is particularly 
useful, for example, as a way to reset the GetGlobal module 
if you are using GetGlobal and SetGlobal (see below) to store 
information during the execution of a loop. Note that First is 
not necessary if you are using GetLocal and SetLocal. #!N #!N 
When a loop is present in a visual program, it causes 
the execution of all modules in the visual program containing the 
looping tool (ForEachN, ForEachMember, or Done), subject to optimization. For this 
reason it is strongly suggested that looping modules NOT be placed 
in the top level visual program, but rather be used only 
within macros. If used within a macro, the macro will not 
output any values until the loop is complete, when the ForEachN 
or ForEachMember list is exhausted or when the Done module causes 
an exit. #!N #!N If a loop occurs inside a macro, 
and you reexecute a visual program calling this macro, the loop 
will not be reexecuted as long as the result of the 
macro remains in the cache. However, the presence of a side 
effect module (such as WriteImage or Print) inside of a loop 
will cause the loop to be reexecuted regardless of whether the 
output of the macro remains in the cache. If this is 
not the desired behavior, Route can be used to turn off 
the entire macro. #!N #!N For efficiency you might find it 
desirable to set the caching option to  #!F-adobe-times-bold-r-normal--18*   Last Result #!EF 
for modules within the loop. In this way, multiple intermediate values 
within a loop will not use up valuable cache space. #!N 
#!N Note that the full execution of a loop is considered 
to occur within a single execution of the graph (as would 
occur if you select Execute Once from the Execute menu). Thus 
if you change any interactor values DURING the execution of the 
loop, those interactor values will not take effect until the loop 
is complete. This is an important way in which looping differs 
from using the Sequencer; if you change the value of an 
interactor while the Sequencer is running, the value will be updated 
on the next frame of the sequence. #!N #!N #!N  #!F-adobe-times-medium-i-normal--18*   
Next Topic #!EF #!N #!N  #!Lstates,dxall269 h Preserving Explicit State  #!EL  #!N  #!F-adobe-times-medium-i-normal--18*   #!N