I've been playing around with a few C interpreters and have found
picoC to look like it meets all my needs.
to kick off a script you call
void PicocCallMain(int argc, char **argv); which recursively calls the internal
parser etc..
Is it possible to recode picoC so that I could run scripts iteratively.
for example.
while(1)
{
picoCyield(&script1);
picoCyield(&script2);
}
each call to picoCyield would call the token reader no more than required to
execute the smallest possible block of script.
I could run picoC as is with threads, but I the enviorment I am working in
prohibits it..
Any help, or pointers to a similair interpreter that can do this, would
be greatly appreciated.
I would look at the top-level code for interactive mode. Where it currently prints the prompt and waits for input, I would replace with a callback to your program which you would use to provide the next statement. Then all the line-by-line execution is already done for you.
Related
I am trying to call a do file which has loops from a program in other do file. I am getting an error.
Now, if I use do instead of include, it runs fine but I don't get to use local macros created. I used include so I can use the macros further in the program. I don't want to use global.
First do file (test.do).
forval i = 1/5 {
local val`i' = `i'
}
Second do file(call-test.do)
capture program drop test
program test
include "test.do"
di `val1'
end
test
I got error r(9611);
I using version 16.1
Response from Stata support
The -include- is designed to let you share definitions. It will not
work correctly within a program as documented in -help include-
The short answer is that -include- is usually ok to use in programs,
but not with looping commands, and if you use -include- in a program,
it probably isn't working the way you think it is.
Here's the long version of exactly what is going on:
When you use -include- in a program, your program literally includes
the -include- command in it. The program does NOT have the contents
of the include file substituted in place. That's the start of the
problem for looping commands.
In any case, when a program executes the -include- command, Stata gets
confused about whether to define a loop program on the behalf of a
looping command globally or within the program, and things go downhill
from there. Given how the code is structured, it is unlikely we could
fix -include- to behave differently, so our documentation really
should simply recommend against using -include- in programs. In
addition, at the point at which the failure occurs, Stata simply knows
that it cannot call a program that it thinks should already be in
memory, hence the 9611 return code. It has no idea at that point that
this was because it was called with -include-, unfortunately.
We could in the future introduce a true C-like "#include" for use in
programs which would simply substitute in-line the lines from whatever
was included into your program
I want to start a program using a batch-file. When I start the program manually (just double-clicking the exe-file) I have to select two file paths manually. I want to make a bat-script which starts the program and passes these two paths as arguments, so that the paths are already set when the program starts. The problem is that I don't know what the program will accept as arguments, or what order the of the arguments should be.
Is there any way of figuring out which arguments an exe-file can take?
If the exe doesn't provide a help output using ? or h as parameter and there is no doc, there is no easy way. Depending on the language the program is written in and whether you are allowed to decompile it or not, you might use tools like Reflector to decompile it and check which arguments are possible. This might help you: How do I decompile a .NET EXE into readable C# source code?
However, most software licenses prohibit decompiling even if they can't prevent it.
I am trying to call a C program from my Ruby script, parsing it an argument (file object) and then store some variables the C program would return.
The idea is that my Ruby script allows me to easily cycle through the files & folders of a parent folder but it is way too slow to efficiently process all the files in that folder. Hence the use of a C program that I want to call to process each file.
My problem is that I can't find a method to call that C program from Ruby (and how to parse it the file argument, I'm not even sure it is possible as I don't know if Ruby files objects and C streams are "compatible")
Thank you in advance for your help !
You say you are trying to call a program so I assume you are not trying to statically or dynamically load a library and call a function. (If you are trying to load a library to call a function then look to the DL::Importer module.)
As for calling an external program from Ruby and receiving its result (from stdout, in this case), regardless of whether it was written in C or not, an easy way to do it is:
value = `program arg1 arg2 ...`
e.g. if the program you want to call compresses a given file and outputs the compressed size.
size = `mycompressionprogram filename.txt`
puts "compressed result is: #{size}"
Note those are back ticks " ` ".
So this is one easy way to code your computationally heavy stuff in C and wrap it up in a Ruby script.
One simple traditional way for a Ruby process to interact with unrelated C code is popen, which will allow your Ruby process to invoke the (compiled) code as a separate process, passing your choice of arguments into the traditional space the operating system allocates for that (accessible in argv in your process's int main(int argc, char** argv)), and then interacting with its standard input and standard output over a pipe. However, this technique launches another process and requires that you serialize/deserialize any ongoing interprocess communication so that it can run over the pipe, which may be an impediment.
So you can also write the C code as a Ruby extension, which will allow you to return values more readily, and moreover avoids the overhead associated with having a separate process involved. However, note that if you perform extensive work with Ruby objects in your C code you may still incur the performance penalties you'd hoped to avoid. The canonical document on how to write Ruby extensions is README.EXT.
I need to run a program that crawls websites and I already have an algorithm and some parts of the code. Problem is, I do not know how to insert wget into my source code. Our student assistant hinted that some kind of keyword or function shall be used before the wget( system, I think or something but I'm not so sure).
when to not use system:
1.) when you want to distribute the program to different environment, where the program you call via system is not available
2.) in a security relevant environment, where you have to make sure that the program you call is really the program you want it to be
3.) when the thing you want to do can easily be accomplished in 10-20 lines of C code
4.) in performance-critical applications
so, you should use system virtually never.
instead, to accomplish the same thing, you could use libcurl, as David suggested (his answer seems to be gone...), or do some socket programming (it's C, after all).
In a real-world scenario, I'd probably just default to writing the crawler in a different language. web requests and complex string processing are not necessarily the strong sides of C, and most definitely not very convenient to use :)
You can use the system() command.
In your case (possibly):
system("/bin/wget");
But if you want really call wget with parameters, so you should use execl().
execl("/bin/wget", "http://anyadress.com/file");
Whenever , you want to run shell commands from your C program , you use system("shell command").In your case
system("wget");
Note - wget is an executable , whose location is added to the path variable, so there is no need to specify the path explicitly.
-- Example --
#include <stdio.h>
#define BUFFLEN 2500
int main()
{
char web_address[BUFFLEN] = "www.google.com";
system("wget 'web_address' ");
return 0;
}
The system command is used to execute a shell command. man system
I want to trace each path of function calls.
For eg:
int a()
{
b();
return 1;
}
void b()
{
}
int main()
{
int x=a();
return 0;
}
So my call trace is main->a->b
In this manner I want to trace each set paths of calls.
I have thought of a depth first search. But i am not sure how this would go.
Can anyone suggest me any concrete method to be implemented in perl?
I will have C program file and will run a perl script over it to get call traces.
There are a number of free call-graph programs listed in this article, including egypt which is a small Perl script that uses gcc and Graphviz to generate the static call graph of a C program.
One way is automatically instrument the source code with probes that collect the information you want as the program runs. You can use a program transformation tool to do that.
Here's a paper on how do collect information abouth "which blocks" get executed, using a transformation system to insert such probes. A very small change to the specification of where to put probes, and some minor work to capture the current function would accomplish what you want in a relaible way.
I believe Doxygen can do just that.