When looking at some of our logging I've noticed in the profiler that we were spending a lot of time in the operator<< formatting ints and such. It looks like there is a shared lock that is used whenever ostream::operator<< is called when formatting an int(and presumably doubles). Upon further investigation I've narrowed it down to this ...
I'm trying to hold the screen on my output using the header file <iostream.h>, but I don't know any equivalent function to the getch() & clrscr() functions of <conio.h> in <iostream.h> or any other C++ library. Are there any such functions? ...
I am very new to C++ and I am wondering how you output/write variables declared as double to a txt file. I know about how to output strings using fstream but I cant figure out how to send anything else. I am starting to think that you can't send anything but strings to a text file is that correct? If so then how would you convert the inf...
Consider this line: std::wcout << "Hello World!"; Is it OK to pass char* or char to wide stream? ...
Say I want to read the contents of a file using basic_filebuf. I have a type called boost::uintmax_t which has a size of 8 bytes. I am trying to write the following: typedef basic_filebuf<uintmax_t> file; typedef istreambuf_iterator<uintmax_t> ifile; file f; vector<uintmax_t> data, buf(2); f.open("test.txt", std::ios::in | std::ios::b...
I am writing a Java application that uses a C++ library through a JNI interface. The C++ library creates objects of type Foo, which are duly passed up through JNI to Java. Suppose the library has an output function void Foo::print(std::ostream &os) and I have a Java OutputStream out. How can I invoke Foo::print from Java so that...
I have to read a lot of data into: vector<char> A 3rd party library reads this data in many turns. In each turn it calls my callback function whose signature is like this: CallbackFun ( int CBMsgFileItemID, unsigned long CBtag, void* CBuserInfo, int CBdataSize, void* CBdataBuffe...
I know that there is no concept of threads in current C++, but this article is saying: A typesafe, threadsafe, portable logging mechanism ..... The fprintf() function is threadsafe, so even if this log is used from different threads, the output lines won't be scrambled. What about cout, cerr and clog? I think thi...
I'm creating a logger with the following sections: // #define LOG(x) // for release mode #define LOG(x) log(x) log(const string& str); log(const ostream& str); With the idea to do: LOG("Test"); LOG(string("Testing") + " 123"); stringstream s; LOG(s << "Testing" << 1 << "two" << 3); This all works as intended, but when I do: LOG(s...
Hello, I usually use stringstream to write into in-memory string. Is there a way to write to a char buffer in binary mode? Consider the following code: stringstream s; s << 1 << 2 << 3; const char* ch = s.str().c_str(); The memory at ch will look like this: 0x313233 - the ASCII codes of the characters 1, 2 and 3. I'm looking for a wa...
Iostream, when all of the files it includes, the files that those include, and so on and so forth, adds up to about 3000 lines. Consider the hello world program, which needs no more functionality than to print something to the screen: #include <iostream> //+3000 lines right there. int main() { std::cout << "Hello, World!"; retu...
So that you could do something like this, for instance: std::string a("01:22:42.18"); std::stringstream ss(a); int h, m, s, f; ss >> h >> m >> s >> f; Which normally requires the string to be formatted "01 22 42 18". Can you modify the current locale directly to do this? ...
I was hoping to get some opinions regarding best practices and comments on the way I read user input from the command line. Is there a recommended way to do this, am I using the try/catch blocks properly? My example here works fine, but would still like to hear if there is a 'cleaner' way to do this. Many thanks. For example are he retu...
I call a service which returns a gzipped file. I have the data as an InputStream (courtesy of javax.activation.DataHandler.getInputStream();) from the response. What I would like to do is, without writing anything to disk, get an InputStream of the decompressed data in the file that is in the archive. The compressed file in this case i...
I'd like to compose two (or more) streams into one. My goal is that any output directed to cout, cerr, and clog also be outputted into a file, along with the original stream. (For when things are logged to the console, for example. After closing, I'd like to still be able to go back and view the output.) I was thinking of doing somethin...
I've been writing a custom std::streambuf as part of a logging system. However, I'm having problems with the first piece of output from a stream not being formatted correctly. Here's a reduced test-case that doesn't use any custom streambuf or ostream classes: #include <iostream> int main() { std::streambuf *coutbuf = std::cout.rd...
Is there anyway to read a known number of bytes, directly into an std::string, without creating a temporary buffer to do so? eg currently I can do it by boost::uint16_t len; is.read((char*)&len, 2); char *tmpStr = new char[len]; is.read(tmpStr, len); std::string str(tmpStr, len); delete[] tmpStr; ...
In C++ we always put the following at the top of the program #include <iostream> What about for C? ...
Follow up of this question: When I do include <iostream> . It happens that it includes many files from /usr/include .A grep "\usr\include" over g++ -E prog.cpp counted to about 1260 entries ;). Is their a way to control including various files? Platform: Linux G++ version: 4.2.4 ...
I need to overload the stream extraction operator. I need to do this by allowing a user to input a string of characters at a prompt, say "iamastring", and then the operator would extract each character from the string and test whether or not it is whitespace and if it is not whitespace store it in a character array which is then passed ...