C fopen is a C library function used to open an existing file or create a new file.
The basic format of fopen is:
Syntax:
FILE *fopen( const char * filePath, const char * mode );Parameters
- filePath: The first argument is a pointer to a string containing the name of the file to be opened.
- mode: The second argument is an access mode.
C fopen() access mode can be one of the following values:
| Mode | Description |
|---|---|
| r | Opens an existing text file. |
| w | Opens a text file for writing if the file doesn't exist then a new file is created. |
| a | Opens a text file for appending(writing at the end of existing file) and create the file if it does not exist. |
| r+ | Opens a text file for reading and writing. |
| w+ | Open for reading and writing and create the file if it does not exist. If the file exists then make it blank. |
| a+ | Open for reading and appending and create the file if it does not exist. The reading will start from the beginning, but writing can only be appended. |
Return Value
C fopen function returns NULL in case of a failure and returns a FILE stream pointer on success.
Example:
#include<stdio.h>
int main()
{
FILE *fp;
fp = fopen("fileName.txt","w");
return 0;
}- The above example will create a file called fileName.txt.
- The w means that the file is being opened for writing, and if the file does not exist then the new file will be created.
