C++ fopen Function: An In-Depth Guide

In C++, the fopen function is used to open a file and return a pointer to that file. Its syntax is as follows:

FILE *fopen(const char *filename, const char *mode);

filename is the name of the file to be opened, and mode is the mode in which the file is opened, with several options to choose from:
Among them, filename is the name of the file to be opened, and mode is the mode in which the file is opened, with several options to choose from:

1. “r” mode: file must exist and can only be read
2. “w”: writing mode, if the file exists it will be cleared, if it does not exist a new file will be created
3. “Option A: Append mode, adding content to the end of a file, which will create a new file if it doesn’t exist.”
4. “r+”: Read and write mode, file must exist.
5. “w+” mode: clears the file for reading and writing, creates a new file if it doesn’t exist.
6. “a+” : Read and write mode, content will be added to the end of the file, creating a new file if it doesn’t exist.

The fopen function returns a pointer to a FILE structure, and will return NULL if the opening is unsuccessful. After using the file, it is recommended to close it using the fclose function.