Use fopen function to open a file for reading
Syntax
C fopen function has the following format.
FILE *fopen(const char *fname, const char *mode); Header
C fopen function
is from header file stdio.h.
Description
C fopen function opens a file by *fname and returns a FILE pointer on success or NULL pointer on failure.
The legal values for mode.
| Mode | Meaning |
|---|---|
| "r" | Open text file for reading |
| "w" | Create a text file for writing |
| "a" | Append to text file |
| "rb" | Open binary file for reading |
| "wb" | Create binary file for writing |
| "ab" | Append to a binary file |
| "r+" | Open text file for read/write |
| "w+" | Create text file for read/write |
| "a+" | Open text file for read/write |
| "rb+" or "r+b" | Open binary file for read/write |
| "wb+" or "w+b" | Create binary file for read/write |
| "ab+" or "a+b" | Open binary file for read/write |
Example
The correct method of opening a file:
#include <stdio.h>
#include <stdlib.h>
//from www . j a v a 2 s . c o m
int main(int argc, char *argv[])
{
FILE *fp;
if ((fp = fopen("test", "w"))==NULL) {
printf("Cannot open file.\n");
exit(1);
}
fclose(fp);
}
This fragment opens a file called TEST for binary read/write operations:
#include <stdio.h>
#include <stdlib.h>
/* www. j a v a 2 s . c o m*/
int main(int argc, char *argv[])
{
FILE *fp;
if((fp=fopen("test", "rb+"))==NULL) {
printf("Cannot open file.\n");
exit(1);
}
fclose(fp);
}