C language file operations

"RT" only opens a text file and only supports reading data.
"WT" only writes to open or create a text file, only data can be written
Append "at" to open a text file and write data at the end of the file.
"Rb" is used to open a binary file and only read data.
"WB" only writes to open or create a binary file, only data can be written
Append "AB" to open a binary file and write data at the end of the file.
"RT +" reads and writes to open a text file, allowing reading and writing
"WT +" reads and writes to open or create a text file, allowing reading and writing
"At +" to open a text file, allow reading, or append data at the end of the file
"RB +" reads and writes a binary file, allowing reading and writing
"WB +" to open or create a binary file and allow reading and writing
"AB +" reads and writes to open a binary file, allowing reading or appending data at the end of the file

The usage of files is described as follows:

The usage of a file is composed of R, W, A, T, B, and +. The meanings of each character are as follows:

R (read): Read
W (write): Write
A (append): append
T (text): Text File, can be omitted without writing
B (banary): Binary File