Function fopen () in C

The function FILE * fopen (const char * filename, const char * mode) in Library C opens the file pointed to the filename parameter by using the given mode.

Declare function fopen () in C

Below is the declaration for the function fopen () in C:

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

Parameters

filename - This is the string containing the file name to be opened.

mode - This is the string containing a file access mode. It includes:

mode Description "r" Open a file to read. File must exist "w" Create an empty file to write. If a file with the same name already exists, its content is removed and the file is treated as a new blank file "a" Append to a file. With write operations, append data at the end of the file. The file is created if it does not already exist "r +" Open a file to write and read. File must exist "w +" Create an empty file to write and read "a +" Open a file to read and append

Returns the value

This function returns a FILE pointer. Otherwise, NULL is returned and the errno global variable is set to indicate an error.

For example

The following C program illustrates the usage of the function fopen () in C:

 #include #include int main () { FILE * fp ; fp = fopen ( "baitapc.txt" , "w+" ); fprintf ( fp , "%s %s %s %s" , "Chung" , "toi" , "la" , "QTMTeam" ); fclose ( fp ); return ( 0 ); } 

Compiling and running the above program will create a baitap.t.txt

Now follow the contents of the above file by using the following C program:

Compile and run the above C program to see the results:

According to Tutorialspoint

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