fopen() function is used to open a file whose name is pointed to by fname and returns the stream that is associated with it. The type of operations that can be allowed on the file are defined by value of mode
Following table lists the legal value for mode that can be allowed on the file :
C Programming Table:| Mode | Meaning |
|---|---|
| "r" | Open a text file for reading |
| "w" | Create a text file for writing |
| "a" | Append content to text file |
| "rb" | Open a binary file for reading |
| "wb" | Create a binary file for writing |
| "ab" | Append content to a binary file |
| "r+" | Open text file for read and write both |
| "w+" | Create a text file for read and write both |
| "a+" | Open a text file for read and write(append) both |
| "rb+" or "r+b" | Open a binary file for read and write both |
| "wb+" or "w+b" | Create a binary file for read and write both |
| "ab+" or "a+b" | Open a binary file for read and write(append) both |
#include<stdio.h> FILE *fopen(const char *fname, const char (mode);
A FILE pointer is returned if fopen() function is successful in opening the specified file, otherwise it will returns a null pointer
Following c code shows the correct method to open a file:
FILE *fp;
fp=fopen("demo.txt", "w");
if(fp==NULL)
{
printf("Error in opening the file..!!\n");
printf("Press any key to exit..\n");
getch();
exit(1);
}