stdout
Author
not sure that this is the correct place for this but i need help in dealing with stdout
iknow how to redirect stdout from the console to a file
but i need stdout to go to the console AND a log file
i cant find any information on google about copying this
any help please
Assuming you are using C++, you could write a function that writes it to the console through cout, and writes it to a file using fstream. If you're using SDL, anything using cout automatically goes to stdout.txt.
Author
c++ devc++ windows
yes Oberon thats what i'm trying to do but i dont know how to catch the stuf from cout
all i have been able to find information on is redirecting to a file, nothing more
this is what i found for the file redirection
if( freopen("Logfile.txt", "w", stdout) == NULL)
{
MessageBox(NULL,"Error Redirecting stdout", "Error", MB_OK);
}
else
{
setbuf( stdout, NULL );
}
i just cant find out how to intercept stdout
is there a way that stdout will be driected into a function instead of the console?
ADD::
ohh
can i use window's SetStdHandle to set the stdout into a pipe and then read it later?
thats all i cant think of sleep is pulling me down now....
zzzzzzzzzzzzzzzzz
yes Oberon thats what i'm trying to do but i dont know how to catch the stuf from cout
all i have been able to find information on is redirecting to a file, nothing more
this is what i found for the file redirection
if( freopen("Logfile.txt", "w", stdout) == NULL)
{
MessageBox(NULL,"Error Redirecting stdout", "Error", MB_OK);
}
else
{
setbuf( stdout, NULL );
}
i just cant find out how to intercept stdout
is there a way that stdout will be driected into a function instead of the console?
ADD::
ohh
can i use window's SetStdHandle to set the stdout into a pipe and then read it later?
thats all i cant think of sleep is pulling me down now....
zzzzzzzzzzzzzzzzz
May I ask why you're using stdout when you could be using cout just as easily? In fact, its probably a little bit more easier! Just a question though. If you aren't sure on how to use cout, its rather easily:
Just some examples! Good luck!
#include <iostream> // for std::cout, cin, endl#include <string>using namespace std;int main(void){ cout << "Hello World" << endl; cout << "Hello" << ' ' << "World" << endl; string szLine("Hello World"); cout << szLine << endl;}Just some examples! Good luck!
The easiest method to do this would probably to spawn a child process that used the C++ stream facility to direct output to both a file and stdout, using a pipe to redirect the parent's stdout to the child's stdin.
Here is an article creating a child process with redirected standard in and here is source to a program that would dump stdin to a file and stdout.
Here is an article creating a child process with redirected standard in and here is source to a program that would dump stdin to a file and stdout.
#include <iostream>#include <fstream>class twinbuf : public std::streambuf { protected: std::streambuf * buf1_; std::streambuf * buf2_; public: twinbuf(std::streambuf * buf1, std::streambuf * buf2) : buf1_(buf1), buf2_(buf2) {} virtual ~twinbuf() { sync(); } protected: virtual int_type overflow (int_type c) { if (c != EOF) { buf1_->sputc(traits_type::to_char_type(c)); buf2_->sputc(traits_type::to_char_type(c)); } return c; } virtual int sync () { if (buf1_->pubsync() == -1) return -1; if (buf2_->pubsync() == -1) return -1; return 0; }};int main(int argc, char ** argv) { if (argc != 2) { return -1; } std::ofstream ofs(argv[1]); if (!ofs.good()) { return -1; } twinbuf twin(ofs.rdbuf(), std::cout.rdbuf()); std::cout.rdbuf(&twin); std::cout << std::cin.rdbuf(); return 0;}
Author
thanks sicrane thats what i was looking for
does the child process continually dump what it recieves or does it need a while/for statement to output the redirected stuff
now i have my main program create a pipe
create the child process and pass the pipe's read handle to the child
and the child dups it to a console and file
until the parent exits or dies
my head hurts
does the child process continually dump what it recieves or does it need a while/for statement to output the redirected stuff
now i have my main program create a pipe
create the child process and pass the pipe's read handle to the child
and the child dups it to a console and file
until the parent exits or dies
my head hurts
With the source code from above, the child will keep dumping as long as std::cin doesn't fail (like with a borken pipe), so you don't need an explicit while loop.
Author
ok i have this
the text appears in the console window but the log file is empty and i dont think that the output from my app is traveling through the pipe into the child
in the child process if i add a cout << "whatever" before the std::cout << std::cin.rdbuf();
it appears in the log twice but not in the console
if i place it after std::cout << std::cin.rdbuf(); noting come out any where
int CreateListener(void){// create a pipe SECURITY_ATTRIBUTES saAttr; bool fSuccess; // Set the bInheritHandle flag so pipe handles are inherited. saAttr.nLength = sizeof(SECURITY_ATTRIBUTES); saAttr.bInheritHandle = TRUE; saAttr.lpSecurityDescriptor = NULL; // Create a pipe for the child process's STDOUT. if (! CreatePipe(&piperead, &pipewrite, &saAttr, 0)) return 0; // set the stdoutput SetStdHandle(STD_OUTPUT_HANDLE,pipewrite);// start up the child with pipe handle PROCESS_INFORMATION piProcInfo; STARTUPINFO siStartInfo; bool CreateRet = false; // Set up members of the PROCESS_INFORMATION structure. ZeroMemory( &piProcInfo, sizeof(PROCESS_INFORMATION) ); // Set up members of the STARTUPINFO structure. ZeroMemory( &siStartInfo, sizeof(STARTUPINFO) ); siStartInfo.cb = sizeof(STARTUPINFO); siStartInfo.hStdError = GetStdHandle(STD_ERROR_HANDLE); siStartInfo.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE); siStartInfo.hStdInput = piperead; siStartInfo.dwFlags |= STARTF_USESTDHANDLES; // Create the child process. CreateRet = CreateProcess(listenerexe, listenerlogfile, // command line NULL, // process security attributes NULL, // primary thread security attributes TRUE, // handles are inherited 0, // creation flags NULL, // use parent's environment NULL, // use parent's current directory &siStartInfo, // STARTUPINFO pointer &piProcInfo); // receives PROCESS_INFORMATION if (CreateRet == 0) return 0; else { CloseHandle(piProcInfo.hProcess); CloseHandle(piProcInfo.hThread); } return 1;}the text appears in the console window but the log file is empty and i dont think that the output from my app is traveling through the pipe into the child
in the child process if i add a cout << "whatever" before the std::cout << std::cin.rdbuf();
it appears in the log twice but not in the console
if i place it after std::cout << std::cin.rdbuf(); noting come out any where
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