I can not display the value of the string in conky, tell me where the errors are.
my function call:
${lua conky_func}
conky.config section:
lua_load = '/home/user/.conky/function.lua',
result:
conky: llua_getstring: function conky_func didn't return a string, result discarded
$ lua
Lua 5.3.6 Copyright (C) 1994-2020 Lua.org, PUC-Rio
> function conky_func()
result = os.execute("ps aux | awk '{sum+=$6} END {print sum/1024}'; exit")
return result
end
> conky_func()
4902.65
true
> ^C
Where are the errors, please help.
The variable result appears to be a floating point number rather than a string. I haven't tested it, but I'd try changing return result to return string.format("%f2", result). See 6.4 – String Manipulation in the Lua Reference Manual and documentation on sprintf in the C reference section of cppreference.com for more information.
Related
In various languages, hex values shows as \xhh values in a string literal by using the \x escape sequence
I using encrypting library in lua and hex ouptut is like:
e6dd6bf41a97b89980b2bc2e838bd1bb746b83139b4c1e7c73bdedcc18a01ec24e26703a60cc19d29750c22084470da889e67375afcd9b12595748f6b6ce2d7b436d56ab84e70c819ef52b1edf63148b0ee2cce672ff4d57115c7b51abaaf8a7
but in python library output is:
\xe6\xddk\xf4\x1a\x97\xb8\x99\x80\xb2\xbc.\x83\x8b\xd1\xbbtk\x83\x13\x9bL\x1e|s\xbd\xed\xcc\x18\xa0\x1e\xc2N&p:`\xcc\x19\xd2\x97P\xc2 \x84G\r\xa8\x89\xe6su\xaf\xcd\x9b\x12YWH\xf6\xb6\xce-{CmV\xab\x84\xe7\x0c\x81\x9e\xf5+\x1e\xdfc\x14\x8b\x0e\xe2\xcc\xe6r\xffMW\x11\\{Q\xab\xaa\xf8\xa7
how can i convert Hex number to Hex escaped sequence?
Here is an example code, some characters may fall out, but the gist is this:
local s= [[e6dd6bf41a97b89980b2bc2e838bd1bb746b83139b4c1e7c73bdedcc18a01ec24e26703a60cc19d29750c22084470da889e67375afcd9b12595748f6b6ce2d7b436d56ab84e70c819ef52b1edf63148b0ee2cce672ff4d57115c7b51abaaf8a7]]
function escape (s)
return string.gsub(s, '..', function (c)
local ch = tonumber(c,16)
if ch==10 then return '\\n'
elseif ch==13 then return '\\r' -- 9 and \\t ?
elseif ch==92 then return '\\\\'
elseif 0x1F<ch and ch<0x7f then return string.char(ch)
else return string.format("\\x%s", c)
end
end)
end
print (escape (s) )
maybe there are more elegant solutions with definition of exception characters.
I'm using Matlab Coder to convert some Matlab code to C++, however I'm having trouble converting intergers to strings.
int2str() is not supported for code generation, so I must find some other way to convert ints to strings. I've tried googling it, without success. Is this even possible?
This can be done manually (very painful, though)
function s = thePainfulInt2Str( n )
s = '';
is_pos = n > 0; % //save sign
n = abs(n); %// work with positive
while n > 0
c = mod( n, 10 ); % get current character
s = [uint8(c+'0'),s]; %// add the character
n = ( n - c ) / 10; %// "chop" it off and continue
end
if ~is_pos
s = ['-',s]; %// add the sign
end
sprintf is another very basic function, so it possibly works in C++ as well:
x = int64(1948)
str = sprintf('%i',x)
It is also the underlying function used by int2str.
According to this comprehensive list of supported functions, as pointed out by Matt in the comments, sprintf is not supported, which is surprising. However there is the undocumented helper function (therefore not in the list) sprintfc which seems to work and can be used equivalently:
str = sprintfc('%i',x)
I use the following workaround to enable sprintf for general use with Matlab Coder:
1) Create the following m-file named "sprintf.m", preferably in a folder NOT on your Matlab path:
function s = sprintf(f, varargin)
if (coder.target('MATLAB'))
s = builtin('sprintf',f,varargin{:});
elseif (coder.target('MEX'))
s = builtin('sprintf',f,varargin{:});
else
coder.cinclude('stdio.h');
s = char(zeros(1024,1));
cf = [f,0]; % NULL-terminated string for use in C
coder.ceval('sprintf_s', coder.ref(s(1)), int32(1024), coder.rref(cf(1)), varargin{:});
end
2) Ensure that sprintf is not specified as extrinsic via coder.extrinsic
3) Specify the folder containing the newly created "sprintf.m" as additional include directory when generating code. If you use the codegen function, this can be done via the -I switch. If you use the Coder App, this can be done under "More Settings -> Custom Code -> Additional include directories" from the "Generate" tab.
4) Convert from int to string as follows: s=sprintf('%d',int32(n));
Notes:
The specified "sprintf.m" shadows the built-in sprintf function and executes instead of the built-in function every time you call sprintf from generated code. By placing this file in a folder that is not on the Matlab path, you avoid calling it from other code made to run in Matlab. The coder.target call also helps to navigate back to the built-in function in case this gets called in a normal Matlab session or from a MEX file.
The code above limits the result to 1023 characters (a terminating zero is required at the end). The call to sprintf_s instructs the C++ compiler to throw a runtime exception if the result exceeds this value. This prevents memory corruption that is often only caught much later and is harder to trace back to the offending call. This limit can be modified to your own requirements.
Numeric types must be cast to the correct class before passing them to sprintf, e.g. cast to int32 to match a %d in the format string. This requirement is the same when using fprintf with Matlab Coder. However, in the fprintf case, Matlab Coder catches type errors for you. For sprintf, the C++ compiler may fail or the resulting string may contain errors.
String arguments must be NULL-terminated manually to be used in C calls, as Matlab Coder does not do this automatically (credit to Ryan Livingston for pointing this out). The code above ensures that the format string f is NULL-terminated, but NULL-termination of other string arguments remains the responsibility of the calling function.
This code was tested on a Windows platform with a Visual Studio C++ compiler and Matlab R2016a (Matlab Coder 3.1), but is expected to work in most other environments as well.
Edit: As of MATLAB R2018a, sprintf is supported for code generation by MATLAB Coder.
Pre R2018a Answer
You could also call the C runtime sprintf or snprintf using coder.ceval. This has the benefit of making supporting floating point inputs easy as well. You can also change the formatting as desired by tweaking the format string.
Supposing that your compiler provides snprintf one could use:
function s = cint2str(x)
%#codegen
if coder.target('MATLAB')
s = int2str(x);
else
coder.cinclude('<stdio.h>');
assert(isfloat(x) || isinteger(x), 'x must be a float or an integer');
assert(x == floor(x) && isfinite(x), 'x must be a finite integer value');
if isinteger(x)
switch class(x)
% Set up for Win64, change to match your target
case {'int8','int16','int32'}
fmt = '%d';
case 'int64'
fmt = '%lld';
case {'uint8','uint16','uint32'}
fmt = '%u';
otherwise
fmt = '%llu';
end
else
fmt = '%.0f';
end
% NULL-terminate for C
cfmt = [fmt, 0];
% Set up external C types
nt = coder.opaque('int','0');
szt = coder.opaque('size_t','0');
NULL = coder.opaque('char*','NULL');
% Query length
nt = coder.ceval('snprintf',NULL,szt,coder.rref(cfmt),x);
n = cast(nt,'int32');
ns = n+1; % +1 for trailing null
% Allocate and format
s = coder.nullcopy(blanks(ns));
nt = coder.ceval('snprintf',coder.ref(s),cast(ns,'like',szt),coder.rref(cfmt),x);
assert(cast(nt,'int32') == n, 'Failed to format string');
end
Note that you'll possibly need to tweak the format string to match the hardware on which you're running since this assumes that long long is available and maps 64-bit integers to it.
I'm trying to do a function in Lua that swaps the characters in a string.
Can somebody help me ?
Here is an example:
Input = "This LIBRARY should work with any string!"
Result = "htsil biaryrs ohlu dowkrw ti hna ytsirgn!"
Note: The space is also swapped
Thank You Very Much :)
The simplest and clearest solution is this:
Result = Input:gsub("(.)(.)","%2%1")
This should do it:
input = "This LIBRARY should work with any string!"
function swapAlternateChars(str)
local t={}
-- Iterate through the string two at a time
for i=1,#str,2 do
first = str:sub(i,i)
second = str:sub(i+1,i+1)
t[i] = second
t[i+1] = first
end
return table.concat(t)
end
print(input)
print(swapAlternateChars(input))
Prints:
This LIBRARY should work with any string!
hTsiL BIARYRs ohlu dowkrw ti hna ytsirgn!
If you need the output as lower case you could always end it with:
output = swapAlternateChars(input)
print(string.lower(output))
Note, in this example, I'm not actually editing the string itself, since strings in Lua are immutable. Here's a read: Modifying a character in a string in Lua
I've used a table to avoid overhead from concatenating to a string because each concatenation may allocate a new string in memory.
I am new to Ada and currently trying to write a simple program involving an if-else if statement. The code is as follows:
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Year_Codes is
Year : String(1..9) := " ";
CharsRead : Natural;
function YearCode(Name : in String) return Integer is
begin
if(Name = "freshman")then
return 1;
elsif(Name = "sophomore")then
return 2;
elsif(Name = "junior")then
return 3;
elsif(Name = "senior")then
return 4;
else
return 0;
end if;
end YearCode;
begin
Put("Enter your academic year: "); -- Prompt for input
Get_Line(Year, CharsRead); -- Input
Put( YearCode(Year) ); -- Convert and output
New_Line;
end Year_Codes;
I am getting 0 for every answer. Any input on what I am doing wrong?
The "=" operation on strings compares the entire strings. If the user's input is "freshman", the value of Name will be "freshman ", not "freshman". Read the documentation for the Get_Line procedure.
You should probably pass YearCode a slice of the Year string, not the entire string; CharsRead tells you what that slice should be.
Specifically, the call should be:
Put( YearCode(Year(Year'First..CharsRead)) );
Here's a case-insensitive version using attributes:
function YearCode(Name : in String) return Integer is
Type Class is (Freshman, Sophmore, Junior, Senior);
begin
Return 1 + Class'Pos(Class'Value(Name));
exception
When CONSTRAINT_ERROR => Return 0;
end YearCode;
With that extra character in your buffer, it looks to me like you are thinking of strings in C terms. You need to stop that. Of everything in the language, string handling is the most different between Ada and C.
While C strings are null terminated, Ada strings are not. Instead, an Ada string is assumed to be the size of the string array object. Its a simple difference, but it has enormous consequences in how you handle strings.
I go into this a bit in my answer to How to I build a string from other strings in Ada? The basic gist is that in Ada you always try to build perfectly-sized string objects on the fly.
Sadly, Text_IO input is one place that has traditionally made that really hard, due to its string buffer-based input. In that case, you are forced to use an overly large string object as a buffer, and use the returned value as the end of the defined area of the buffer, as Keith showed.
However, if you have a new version of the compiler, you can use the function version of Get_Line to fix that. Simply change your middle two lines to:
Put( YearCode(Get_Line) );
I would like to define a function which returns the string "NaN" or sprintf("%g",val) depending on whether val is a string or a numeric value. Initially I was trying to test if val was defined (using the gnuplot "exists" function) but it seems that I cannot pass any undefined variable to a function (an error is issued before the function is evaluated). Therefore: is there a way to test inside a function whether the argument is a string or numeric?
I search for a function isstring which I can use somehow like
myfunc(val)=(isstring(val)?"NaN":sprintf("%g",val))
The goal is to output the values of variables without risking errors in case they are undefined. However I need it as a function if I want a compact code for many variables.
Gnuplot doesn't really have the introspection abilities that many other languages have. In fact, it treats strings and numbers (at least integers) very similarly:
print "1"+2 #prints 3
a=1
print "foo".a #prints foo1
I'm not exactly sure how this is implemented internally. However, what you're asking is very tricky to get to work.
Actually, I think your first attempt (checking if a variable exists) is more sensible as type-checking in gnuplot is impossible*. You can pass the variable name to the function as a string, but the problem is that you don't seem to have a handle on the value. All seems lost -- But wait, gnuplot has an eval statement which when given a string will evaluate it. This seems great! Unfortunately, it's a statement, not a function (so it can't be used in a function -- argv!). The best solution I can come up with is to write a function which returns an expression that can be evaluated using eval. Here goes:
def exists_func(result,var)=sprintf("%s=exists('%s')?sprintf('%g',var):'NaN'",result,var,var)
Now when you want to use it, you just prefix it with eval
a=3
eval exists_func("my_true_result","a")
print my_true_result #3
eval exists_func("my_false_result","b")
print my_false_result #NaN
This goes against the grain a little bit. In most programming languages, you'd probably want to do something like this:
my_true_result=exists_func(a)
But alas, I can't figure out how to make that form work.
Of course, the same thing goes here that always goes with eval. Don't use this function with untrusted strings.
*I don't actually know that it's impossible, but I've never been able to get it to work
EDIT
In response to your comment above on the question, I think a function like this would be a little more intuitive:
def fmt(x)=(x==x)?sprintf("%g",x):"NaN"
With this function, your "sentinal/default" value should be NaN instead of "undefined", but it doesn't seem like this should make too much of a difference...(Really, if you're willing to live with "nan" instead of "NaN" you don't need this function at all -- sprintf will do just fine. (Note that this works because according to IEEE, NaN doesn't equal anything (even itself)).
You helped me a lot these days with gnuplot. I want to give you something back because I have found a solution to check if a variable is numeric or not. This helps to decide which operators can be used on it (e.g. == for numbers, eq for strings).
The solution is not very simple, but it works. It redirects gnuplot's print command to a temp file, writes the variable to the file with print myvar and evaluates the file's first line with system("perl -e '<isnumeric(line#1 in temp file)?>' ") (<> is pseudo-code). Let me know if there's room for imrpovements and let me hear your suggestions!
Example: myvar is a float. Any integer (1 or "1") or string value ("*") works too!
myvar = -2.555
# create temporary file for checking if variables are numeric
Int_tmpfle = "tmp_isnumeric_check"
# redirect print output into temp file (existing file is overwritten)
set print Int_tmpfle
# save variable's value to file
print myvar
# check if file is numeric with Perl's 'looks_like_number' function
isnumeric = system("perl -e 'use Scalar::Util qw(looks_like_number); \
open(FLE,".Int_tmpfle."); $line = < FLE >; \
if (looks_like_number($line) > 0) {print qq(y)} ' ")
# reset print output to < STDOUT> (terminal)
set print "-"
# make sure to use "," when printing string and numeric values
if (isnumeric eq "y") {print myvar," is numeric."} else {print myvar," is not numeric."}