C-File-Operation-Modes

Mode	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”
“rb”	“Open for reading in binary mode. If the file does not exist, 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.”
“wb”	“Open for writing in binary mode. If the file exists, its contents are overwritten. If the file does not exist, it will be created.”
“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.”
“ab”	“Open for append in binary mode. Data is added to the end of the file. If the file does not exist, it will be created.”
“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.”
“rb+”	“Open for both reading and writing in binary mode. If the file does not exist, 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.”
“wb+”	“Open for both reading and writing in binary mode. If the file exists, its contents are overwritten. If the file does not exist, it will be created.”
“a+”	“Searches file. If the file is opened successfully fopen( ) loads it into memory and sets up a pointer which 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.”
“ab+”	“Open for both reading and appending in binary mode. If the file does not exist, it will be created.”