I want to test 2 C programs to check it's coverage (line coverage and branch coverage).
I am using gcovr in linux system.
To do this, I have written a Perl Script that will call gcc compiler and read input from the file, then gives test for the coverage of C program.
I have many test suites in the form of files that are given to C program, I am using Perl to automate the input and get the coverage using gcovr.
Of course I've used system command , and backtics in perl to call gcc and gcovr.
The first C program runs well, because the input to the program is read from arguments given.
But for the second C program, I got confused, because the program only accepts input from keyboard or simply put "it is using scanf".
So, how can we provide input to C programs that only accepts input from keyboard (scanf) through terminal linux or using perl with system command ?
scanf accepts input from stdin. You can redirect stdin to a file when you start your program and have the program get its input from that file.
Redirection is a feature of the OS, not a feature of a specific language.
Let's say you want to start your program and you know that this program will accept '10' 'y' and 'n' as input. All you have to do is to create a file with those lines in, by whatever way you can. Let's suppose that this file is named test_1.
You then start the program with tested_program < test_1 and the program will use '10', 'y' and 'n' as its input.
If using the Perl command system is not a strict requirement, you can consider using Open3 instead. It is more advanced than system, and you can specify what to use for STDIN, STDOUT and STDERR. So you can write the input to your C program in a text file, create a handle to that file, and use Open3 to call your C program specifying that file handle as first argument.
Related
I am trying to make a program that can process sentences in C in the POSIX environment. Assume that my program's name is "test". If the user entered just "./test", then my program will ask the user to enter some sentences. This one so far is easy.
However, if the user entered "./test < file.txt", the program should get the characters from that txt file. I do not know how I can get the characters of the file in C. I tried something like file = open(argv[2]);, but it did not work.
I will really appreciate it if you give me the answer to this question.
TL;DR: If you start your program like
./test
and you have to type in the input, then exactly the same program will read from file.txt if you start it as
./test < file.txt
Longer explanation starts here. (The following explanation is not 100% precise, but shall help to get an understanding what is going on in principle.)
In a C program you can open files with fopen. As a return value, fopen gives you a FILE pointer. However, when you start a program under Unix, three FILE pointers are already available. These default FILE pointers are stored in variables named stdin, stdout and stderr.
Of these, stdin can be used to read from, stdout and stderr can be written to. And, stdin is used as default in several C library calls, like, gets or scanf. Similarly, stdout is used by default for calls like printf.
Now, although they are called FILE pointers, they can in fact represent other things than just files. stdin could be a file, but it can also be a console where you can type in stuff.
This latter scenario is what you observe when you start your test program from the shell with the command
./test
In this case, the test process will be started with stdin just using the console from the shell from which you started the test program. Therefore, if in your test program you call, say, gets(), then your program will implicitly read from stdin, which represents the console input that was inherited from the shell. Consequently, in this case the user has to provide input by typing it in.
Now let's look at what happens if you start your process from the shell in the following way:
./test < file.txt
Here, the shell does a bit of extra work before it actually creates your test process. This is because the < file.txt part of your command line is interpreted by the shell - this is not passed as arguments to your program. Instead, what the shell does is, to open the file.txt and, when the test process is started, hand the opened file.txt over to the process such that in your test process stdin is connected to file.txt.
Then, the call to gets() in your program will again read from stdin, but this time stdin is not the console. This time stdin really corresponds to a file, that is, file.txt.
I wrote a program in C and I want to try it with some inputs. The inputs
are not numbers so I can't use a for loop or something like this in the code.
So I want to write a file with inputs and give it to the program so it will take every time (it waits to input) 1 line from the text file or something like this, is it possible?
If your program reads input from stdin - i.e. if you're using a function like gets or scanf to get your input - you can achieve what you're asking about by using input redirection. Let's say you create a file called test_input.dat which contains your test data. If this file and your program reside in the same directory, you can change to that directory using
cd \your_directory
and then run your program, telling it to read input from test_input.dat by doing the following:
your_program < test_input.dat
This will cause your program to read data from test_input.dat instead of from the terminal, and should work the same for most common operating systems (Windows or Unix variants such as Linux, etc).
Best of luck.
I'm now working on a small C program in Linux. Let me explain you what I want to do with a sample Linux command below
ls | grep hello
The above command is executed in the below passion (Let me know if I've got this wrong)
ls command will be executed first
Output will be given to grep command which will again generate output by matching "hello"
Now I would like to write a C program which takes the piped output of one command as input. Means, In the similar passion of how "grep" program was able to get the input from ls command (in my example above).
Similar question has been asked by another user here, but for some reason this thread has been marked as "Not a valid question"
I initially thought we can get this as a command line argument to C program. But this is not the case.
If you pipe the output from one command into another, that output will be available on the receiving process's standard input (stdin).
You can access it using the usual scanf or fread functions. scanf and the like operate on stdin by default (in the same way that printf operates on stdout by default; in the absence of a pipe, stdin is attached to the terminal), and the C standard library provides a FILE *stdin for functions like fread that read from a FILE stream.
POSIX also provides a STDIN_FILENO macro in unistd.h, for functions that operate one file descriptors instead. This will essentially always be 0, but it's bad form to rely on that being the case.
If fact, ls and grep starts at the same time.
ls | grep hello means, use ls's standard output as grep's standard input. ls write results to standard output, grep waits and reads any output from standard input at once.
Still have doubts? Do an experiment. run
find / | grep usr
find / will list all files on the computer, it should take a lot of time.
If ls runs first, then OS gives the output to grep, we should wait a long time with blank screen until find finished and grep started. But, we can see the results at once, that's a proof for that.
How to control programs written in C from asterisk AGI-application in features.conf?
I want to control my program by pushing keys on the telephone (dtmf-tones). I was reading about using pipes for passing on standard I/O. My first idea was:
$ Asterisk | c_program
then have standard output in AGI-script by printf()
The second idea was to use:
$ printf parameter_a >> file
to write to file and then let my c-program read the file and evaluate the contents as parameter.
Has anyone tried out or has experience with similar tasks/problems?
there are no way do like u show.
posible solutions:
1) Run your program with arguments using system(). you can do that with or without AGI.
2) Use linux pipe(special files)
3) Start your program as AGI/EAGI script, your program must work acordinly, see CAGI
4) Use database table(task) and asterisk realtime for put record in it.
most correct is 3) if ur program is not demon and 2,4 if ur program is demon.
also you can use in dialplan
This is with reference to the below question:
Execute program from within a C program
How do I do the same on Windows with Tiny C Compiler?
I need to execute a .exe fro c program and give input to it from within the same C program by using a file or string as source and read the output from it into a string or file.I have been using system() frunction. Any suggesstions or examples are welcome..Thanks in advance
The simplest way if you don't have popen() etc, or you want to avoid the complexity, is to simplly write a data file eg. infile with fwrite() execute the external program with system() and then read outfile.
system("prog.exe <infile >outfile")
Your prog.exe only has to read stdin and write stdout.
This way you can easily test it with the contents of in/out file.
You would normally do this in your tmp directory and then delete them when you are finished.
The only thing to be careful of is the path to the .exe
Google for "windows popen" and you find this link:
lists.trolltech.com/qt-interest/1999-09/thread00282-0.html
The C runtime library also has _popen(), but I would recommend against it.