Canon Camera, Hackers Manual

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C H A P T E R 5 Scripting
5.3.3 Output
The print command can be used to show information on the camera dis-
play. A print command can have an unlimited number of parameters. Pa-
rameters are separated by commas or by semicolons. During output, the
commas appear as space; the semicolons appear as no space. For example:
print "a:", a;"s"
will produce the output
a: 500s
if the variable a has the value of 500. Please note that an output line must
not exceed 25 characters in length.
The command print_screen allows capturing the output into a file.
print_screen n
with
n > 0
switches capturing on. All output written with
print
will go into
file LOG_n.TXT in subfolder CHDK/LOGS/ , too.
n = 0
switches capturing off. For example,
print_screen 5
print "hello"
print_screen 0
print "bye"
will produce a file
LOG_0005.TXT
containing the string “hello”.
Finally, the command cls (clear screen) removes the output produced
with the
print
command from the display.
5.3.4 Conditional clauses
Conditional clauses are built with the if ... then ... else ... endif
construct. For example:
if a < 0 then
b = 3
else
b = 4
endif