1. Binary file operation
1. To perform binary file operations, you need to add ios::binary
2. The use of ofstream and ifstream
ofstream& write(const void* buf, int len);
Write len bytes of the content pointed to by the pointer buf to the file
ifstream& read(void* buf,int len);
Read len bytes from the file and store them in buf
3.bool eof() if(!ifs.eof()){}
The secondary function is to judge whether the end of the file has been reached, if it reaches the end, it returns true, otherwise it returns false
Two, file offset
fstream actually inherits the fetch method and set method, and iostream is his parent class
File reading is get, file writing is put
tellg() Get the file read pointer
tellp() Get the file write pointer
seekg (offset, starting position) Set the file read pointer
seekp(offset, starting position) Set the file write pointer
The offset can be 1, 2 and other numbers
Start position: ios::cur current position ios::beg start position ios::end end position
The read and write offsets are changed by the write stream operation (ofs<<"xxx");
Change the read offset through the read stream operation (fs>>"xxx");
Change the read offset through the read stream operation (ofs>>"xxx");
seekg only changes the read offset
seekp only changes the write offset