ifstream

I'd like to read a file into a struct or class, but after some reading i've gathered that its not a good idea to do something like: int MyClass::loadFile( const char *filePath ) { ifstream file ( filePath, ios::in | ios::binary ); file.read ((char*)this, 18); file.close(); return 0; } I'm guessing if i want to write a file from a struct/class this isn't kosher either: void MyClass::writeFile( string fileName ) { ofstream file( fileName, ofstream::binary ); file.write((char*)this, 18); file.close(); } It sounds like the reason i don't want to do this is because even if the data members of my

original code #include<iostream> #include<fstream> using namespace std; int main() { ofstream arduino_output("/dev/ttyACM0"); ifstream arduino_input("/dev/ttyACM0"); int value; string txt; while(cin >> value){ arduino_output << value << endl; arduino_input >> txt;//I never recieve the "OK" (Which I should get) cout << txt; } arduino_input.close(); arduino_output.close(); return(0); } Here is the problem: cin >> value; arduino_output << value << endl; arduino_input >> txt;//I never recieve the "OK" (Which I should get) cout << txt; but if I do this instead it works: cin >> value; arduino_output

I am trying to declare an ifstream object in a header file as is shown but I get an error saying that it cannot be accessed. I have tried various things such as making it into a pointer instead, initialising in the .c file etc. but my code can't seem to get part the declaration of it. ReadFile.h: #ifndef READFILE_H #define READFILE_H #include "cv.h" #include "highgui.h" #include <iostream> #include <fstream> class ReadFile{ private: std::ifstream stream; public: std::string read(); ReadFile(); // Default constructor ~ReadFile(); // Destructor }; #endif ReadFile.c: #include "ReadFile.h"

I've got a problem with this code: #include <fstream> struct A { A(std::ifstream input) { //some actions } }; int main() { std::ifstream input("somefile.xxx"); while (input.good()) { A(input); } return 0; } G++ outputs me this: $ g++ file.cpp file.cpp: In function `int main()': file.cpp:17: error: no matching function for call to `A::A()' file.cpp:4: note: candidates are: A::A(const A&) file.cpp:6: note: A::A(std::ifstream) After changing it to this it compile (but that is not solving the problem): #include <fstream> struct A { A(int a) { //some actions } }; int main() { std::ifstream input(

I'm using ifstream::read to read a file, ifstream ifs("a.txt"); char buf[1024]; ifs.read(buf, 1024); But a.txt's size might be less than 1000 bytes , so how am I supposed to know how many bytes have been read from ifs ? You can get the amount of characters extracted by the last operation with std::ifstream::gcount : ifstream ifs("a.txt"); char buf[1024]; ifs.read(buf, 1024); size_t extracted = ifs.gcount(); or ifstream ifs("a.txt"); char buf[1024]; size_t extracted = ifs.read(buf, 1024).gcount(); since read(...) returns *this . 来源： https://stackoverflow.com/questions/11720880/ifstreamread