Keithley 2651A Reference Manual page 277

Model 2651A High Power System SourceMeter® Instrument Reference Manual
String library functions
This library provides generic functions for string manipulation, such as finding and extracting
substrings. When indexing a string in Lua, the first character is at position 1 (not 0, as in ANSI C).
Indices may be negative and are interpreted as indexing backward from the end of the string. Thus,
the last character is at position -1, and so on.
String library functions
Function
string.byte(s)
string.byte(s, i)
string.byte(s, i, j)
string.char(···)
string.format(
formatstring,
...)
string.len(s)
string.lower(s)
string.rep(s, n)
string.sub(s, i)
string.sub(s, i, j)
2651A-901-01 Rev. A / March 2011
Description
Returns the internal numeric codes of the characters s[i],
s[i+1], ···, s[j]. The default value for i is 1; the default
value for j is i. Note that numeric codes are not necessarily
portable across platforms.
Receives zero or more integers. Returns a string with length equal
to the number of arguments, in which each character has the
internal numeric code equal to its corresponding argument. Note
that numeric codes are not necessarily portable across platforms.
Returns a formatted version of its variable number of arguments
following the description given in its first argument, which must be
a string. The format string follows the same rules as the printf
family of standard C functions. The only differences are that the
modifiers *, l, L, n, p, and h are not supported and there is an
extra option, q. The q option formats a string in a form suitable to
be safely read back by the Lua interpreter; the string is written
between double quotes, and all double quotes, newlines,
embedded zeros, and backslashes in the string are correctly
escaped when written.
For example, the call:
string.format('%q', 'a string with "quotes" and
\n new line')
will produce the string:
"a string with \"quotes\" and \
new line"
The options c, d, E, e, f, g, G, i, o, u, X, and x all expect a number
as argument. q and s expect a string. This function does not
accept string values containing embedded zeros, except as
arguments to the q option.
Receives a string and returns its length. The empty string "" has
length 0. Embedded zeros are counted, so "a\000bc\000" has
length 5.
Receives a string and returns a copy of this string with all
uppercase letters changed to lowercase. All other characters are
left unchanged. The definition of what an uppercase letter is
depends on the current locale.
Returns a string that is the concatenation of n copies of the
string s.
Returns the substring of s that starts at i and continues until j; i
and j can be negative. If j is absent, it is assumed to be equal to
-1 (which is the same as the string length). In particular, the call
string.sub(s, 1, j) returns a prefix of s with length j, and
string.sub(s, -i) returns a suffix of s with length i.
Section 6: Instrument programming
6-33