Using realloc() in C

This functionfopen()Open the file pointed to by the pointer and read or write to the file. In write mode, use "w", in read mode, use "r".

If a file exists in the directory, it is treated as a new empty file and its content is overwritten with new data.

This isfopen()C language syntax,

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

Here,

filename-The name of the file to be opened.

acess_mode-Access modes to files, such as read or write modes.

This isfopen()C language example,

Assuming we have a file named "one.txt" containing the following content.

This is demo text!
This is demo text!
This is demo text!

Now, let's look at an example.

Example

#include <stdio.h>
#include<conio.h>
void main () {
　　　FILE　*f;
　　　int len;
　　　f = fopen("one.txt", "r");
　　　if(f == NULL) {
　　　　　　perror("Error opening file");
　　　　　　return(-1;
　　　}
　　　fseek(f, 0, SEEK_END);
　　　len = ftell(f);
　　　fclose(f);
　　　printf("Size of file: %d bytes", len);
　　　getch();
}

Output result

Size of file:　78　bytes

In the above program, the file type pointer variable is declared as f and is used tofopen()The function opens a file named "one.txt".

FILE　*f;
int len;
f = fopen("one.txt", "r");