} Get Current Position In file long int file_index = ftell(file1) Flush File (Write any unwritten data to the file) fflush(file1) Get File Size Int Result = stat("/etc/network/interfaces", &sb) std::ofstream output_file("/home/pi/my_filename/", std::ios_base::app) //Will append to an existing file Std::ofstream output_file("/home/pi/my_filename/") //Will overwrite an existing file “/home/pi/my_directory/nf” (the directory must already exist or reading and writing will fail) Write Text File #include Note that in this example the file will be read and written to the “current directory”, which if you don’t run the executable from the same directory as the executable file is in will not be in the directory where the executable is! To avoid this specify a fixed directory in the filename path, e.g. Printf("File opened, some byte values: %i %i %i %i\n", file_data, file_data, file_data, file_data) įwrite(&file_data, sizeof(unsigned char), 100, file1) Read Write Binary File //OPEN CONFIG FILE IN OUR APPLICAITONS DIRECTORY OR CREATE IT IF IT DOESN'T EXISTįread(&file_data, sizeof(unsigned char), 100, file1) “a+” – Opens the text file for reading and appending the appending operation includes the removal of the EOF marker before new data is written to the file and the EOF marker is restored after writing is complete creates the file first if it doesn’t exist. “a” – Opens the text file for writing at the end of the file (appending) without removing the EOF marker before writing new data to the file this creates the file first if it doesn’t exist. If the file exists, its contents are destroyed. “w+” – Opens the text file as an empty file for both reading and writing. “w” – Opens the text file as an empty file for writing. “r+” – Opens the text file for both reading and writing. This fails if the file does not exist or cannot be found. “ab+” or “a+b” – Opens the binary file for reading and appending the appending operation includes the removal of the EOF marker before new data is written to the file and the EOF marker is restored after writing is complete creates the file first if it doesn’t exist. “ab” – Opens the file for writing at the end of the file (appending) without removing the EOF marker before writing new data to the file this creates the file first if it doesn’t exist. “wb+” or “w+b” – Opens the binary file as an empty file for both reading and writing.
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“wb” – Opens the binary file as an empty file for writing. “rb+” or “r+b” – Opens the binary file for both reading and writing.
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“rb” – Opens the binary file for reading. Headers #include Opening A File File mode specifiers if you always work with your file as a BYTE array you’re fine).īinary files are therefore often more useful to use than text files (and can also be used to store text). This issue is avoided by always specifying the layout of files in bytes and where larger variables are stored specifying the byte order in which they are stored (i.e. storing int values) the different endian systems will read and write the bytes of larger values in opposite order. The only issue that can occur is moving files between little endian and big endian systems where if a file has been specified using variables bigger than a byte (e.g. Binary files are simply an array of bytes and are always written and read the same regardless of the type of system. The interpretation of text files differs between systems to match their internal ways of working with text, with special byte values for characters such as carriage return, line feed and end of file. There are two types of file: text and binary.