Following is a list of all possible modes in which a file can be opened. The tasks performed by fopen( ) when a file is opened in each of these modes are also mentioned
| Modes | description |
|---|---|
| “r” | Searches file. If the file is opened successfully fopen( ) loads it into memory and sets up a pointer which points to the first character in it. If the file cannot be opened fopen( ) returns NULL. |
| “w” | Searches file. If the file exists, its contents are overwritten. If the file doesn’t exist, a new file is created. Returns NULL, if unable to open file. |
| “a” | Searches file. If the file is opened successfully fopen( ) loads it into memory and sets up a pointer that points to the last character in it. If the file doesn’t exist, a new file is created. Returns NULL, if unable to open file. Operations possible – adding new contents at the end of file. |
| “r+” | Searches file. If is opened successfully fopen( ) loads it into memory and sets up a pointer which points to the first character in it. Returns NULL, if unable to open the file. Operations possible – reading existing contents, writing new contents, modifying existing contents of the file. |
| “w+” | Searches file. If the file exists, its contents are overwritten. If the file doesn’t exist a new file is created. Returns NULL, if unable to open file. Operations possible – writing new contents, reading them back and modifying existing contents of the file. |
| “a+” | Searches file. If the file is opened successfully fopen( ) loads it into memory and sets up a pointer which points to the first character in it. If the file doesn’t exist, a new file is created. Returns NULL, if unable to open file. |
| “a+” | Searches file. If the file is opened successfully fopen( ) loads it into memory and sets up a pointer which points to the first character in it. If the file doesn’t exist, a new file is created. Returns NULL, if unable to open file. Operations possible – reading existing contents, appending new contents to end of file. Cannot modify existing contents |