C Language. W3Schools in English. Lessons for beginners

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C Files

File Handling

In C, you can create, open, read, and write to files by declaring a pointer of type FILE, and use the fopen() function:

FILE *fptr
fptr = fopen(filename, mode);

FILE is basically a data type, and we need to create a pointer variable to work with it (fptr). For now, this line is not important. It's just something you need when working with files.

To actually open a file, use the fopen() function, which takes two parameters:

Parameter Description
filename The name of the actual file you want to open (or create), like filename.txt
mode A single character, which represents what you want to do with the file (read, write or append):

w - Writes to a file
a - Appends new data to a file
r - Reads from a file

Create a File

To create a file, you can use the w mode inside the fopen() function.

The w mode is used to write to a file. However, if the file does not exist, it will create one for you:


FILE *fptr;

// Create a file
fptr = fopen("filename.txt", "w");

// Close the file

Note: The file is created in the same directory as your other C files if nothing else is specified.

On our computer, it looks like this:

Files Create in C
Run example »

Tip: If you want to create the file in a specific folder, just provide an absolute path:

fptr = fopen("C:\directoryname\filename.txt", "w");

Closing the file

Did you notice the fclose() function in our example above?

This will close the file when we are done with it.

It is considered as good practice, because it makes sure that:

  • Changes are saved properly
  • Other programs can use the file (if you want)
  • Clean up unnecessary memory space

In the next chapters, you will learn how to write content to a file and read from it.