ofstream

I have a std::wstring whose size is 139,580,199 characters. For debugging I printed it into file with this code: std::wofstream f(L"C:\\some file.txt"); f << buffer; f.close(); After that noticed that the end of string is missing. The created file size is 109,592,584 bytes (and the "size on disk" is 109,596,672 bytes). Also checked if buffer contains null chars, did this: size_t pos = buffer.find(L'\0'); Expecting result to be std::wstring::npos but it is 18446744073709551615 , but my string doesn't have null char at the end so probably it's ok. Can somebody explain, why I have not all string

I have code that currently does something like the following: ofstream fout; fout.open("file.txt"); fout<<"blah blah "<<100<<","<<3.14; //get ofstream length here fout<<"write more stuff"<<endl; Is there a convenient way to find out the length of that line that is written at the stage I specified above? (in real life, the int 100 and float 3.14 are not constant and can change). Is there a good way to do what I want? EDIT: by length, I mean something that can be used using fseek, e.g. fseek(pFile, -linelength, SEEK_END); You want tellp . This is available for output streams (e.g., ostream,

My professor is very smart but expects complete noobs like me to just know how to program c++ . I don't understand how the fstream function works. I will have a data file with three columns of data. I will have to determine with a logarithm whether each line of data represents a circle, rectangle or triangle - that part is easy. The part I don't understand is how the fstream function works. I think I: #include < fstream > then I should declare my file object? ifstream Holes; then I open it: ifstream.open Holes; // ? I don't know what the proper syntax is and I can't find straightforward

I want 41 output files to use in my project to write text on them. first create a string array list to name those output files then I tried to define an array of ofstream objects and use list to name them, but I get this error that 'outfile' cannot be used as a function . Below is my code: #include <sstream> #include <string> #include <iostream> #include <fstream> using namespace std ; int main () { string list [41]; int i=1; ofstream *outFile = new ofstream [41]; for (i=1;i<=41 ;i++) { stringstream sstm; sstm << "subnode" << i; list[i] = sstm.str(); } for (i=0;i<=41;i++) outFile[i] (list[i].c

I've been using fprintf for a while now and I'd like to ask a question. What is the equivalent of this fprintf line: fprintf(OutputFile, "%s", "SomeStringValue"); using ofstream ? How to use the "%s" in ofstream is what I'd really like to know. How to take the next argument and print it as a string? You don't use it. The equivalent is essentially: std::ofstream x("your_file"); x << "SomeStringValue"; x.close(); Go read about it on any of several reference pages. Such as http://www.cplusplus.com/reference/ostream/ostream/operator%3C%3C/ You can't. You just write the string to the stream. If you

In some code that does a lot of file i/o using std::ofstream , I'm caching the stream for efficiency. However, sometimes I need to change the openmode of the file (e.g. append vs truncate). Here is some similar mock code: class Logger { public: void write(const std::string& str, std::ios_base::openmode mode) { if (!myStream.is_open) myStream.open(path.c_str(), mode); /* Want: if (myStream.mode != mode) { myStream.close(); myStream.open(path.c_str(), mode); } */ myStream << str; } private: std::ofstream myStream; std::string path = "/foo/bar/baz"; } Does anyone know if: There is a way to change

I've been pouring over the format description and source code for the 7z archive format, but I'm still having trouble writing a valid container. I assume I can create an empty container... anyway here's my start: std::ofstream ofs(archivename.c_str(), std::ios::binary|std::ios::trunc); Byte signature[6] = {'7', 'z', 0xBC, 0xAF, 0x27, 0x1C}; Byte major = 0; Byte minor = 3; ofs.write((const char*)signature, 6); ofs.write((const char*)major, 1); ofs.write((const char*)minor, 1); UInt64 offset = 0; UInt64 size = 0; UInt32 crc = 0; ofs.write((const char*)offset, 4); ofs.write((const char*)size, 8);