Canon Camera, Руководство хакера

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C H A P T E R 5 Scripting
lists the contents of the specified directory. The result is returned as a table
of file names. If the function fails,
nil
is returned, followed by an error
message and an error number. If the optional parameter showall is true ,
the list will contain the entries “.” , “..” , and deleted entries, too.
String manipulation functions
The CHDK implements the Lua string manipulation library completely. The
library comes with some powerful functions:
l = string.len(s)
Returns the character length of a string. The same is achieved with the operator # :
l = #s
t = string.rep(s,n)
Returns a string where string s is repeated n times.
t = string.upper(s)
Returns string s converted to upper case.
t = string.lower(s)
Returns string s converted to lower case.
t = string.sub(s, from, to)
Returns a substring of s starting at position from and ending at position to .
Indexes start at 1; negative indexes are counted from the end of the string.
t = string.char(n,...)
Converts the integer parameters to characters and concatenates them to a string.
n = string.char(s, i)
Converts the i-th character of s into an integer. Indexes start at 1; negative indexes
are counted from the end of the string.
t = string.format(f, n1,...)
Formats the content of the parameters n1,... with the help of format description f .
The formatting rules are quite similar to that of the printf() statement of ANSI C.
For example
tag, title = "b", "chdk"
string.format("<%s>%s</%s>", tag, title, tag)
returns
<b>chdk</b>
Often used format characters are the following:
%d %i
Decimal signed integer
%o Octal integer
%x %X
Hex integer
%u Unsigned integer
%c Character