Fopen () R +, W + attribute details

R + hasRead/writeAttribute, starting from the file header,Keep the content not covered in the original file;

W + has read/write attributes,If the file exists during write, it will be cleared and written from scratch..

R open a read-only file.Must exist.
R + open a readable file.Must exist.
W. Open and write only the file. If the file exists, the file length is 0, indicating that the file content will disappear. If the file does not exist, the file is created.
W + open the readable and writable file. If the file exists, the file length is cleared to zero, that is, the file content disappears. If the file does not exist, the file is created.
A. Open and write-only files as an attachment. If the file does not exist, the file will be created. If the file exists, the written data will be added to the end of the file, that is, the original content of the file will be retained.
A + opens readable and writable files by appending them. If the file does not exist, the file will be created. If the file exists, the written data will be added to the end of the file, that is, the original content of the file will be retained.
The preceding morphological string can be added with a B character, such as a combination of Rb, W + B, and AB +. The B character is added to indicate that the file opened by the function library is a binary file, rather than text files. However, this character is ignored in the POSIX System in Linux.