fopen command using "r" or "w"

Why do we need to read and write files? Could u kindly explain the following lines?

fopen(A, 'r')

fopen(B, 'w')

Answer 1

[Image Analyst]

You don't need to. If you don't need to import data from a file and don't need to output data to a file, then you don't need to use those functions. Only use them if you need to import or export data. If you use them, be sure you also use fclose().

[Giovanni Ponce]

Could you explain what 'r' means when using it with fopen?

[Walter Roberson]

@Giovanni Ponce

'r' requests "read" access to the file. 'r' is the default if you do not specify the kind of access you need. "r" by itself requests the default "binary" file access; if you want to treat the file as a text file (possibly created on Windows) request "rt" (Read, Text)

If you open a file for read access, then it is permitted to fseek() inside the file. However it is not possible to write to the file; attempting to write will either give an error or else the writes will simply not happen.