Write c programs for file operations. (C #20)

 #include <stdio.h>

int main(void) {

    // Open a file for writing

    FILE *fp = fopen("test.txt", "w");

    // Write some text to the file

    fprintf(fp, "Hello, world!\n");

    fprintf(fp, "This is a test.\n");

    // Close the file

    fclose(fp);

    // Open the file for reading

    fp = fopen("test.txt", "r");

    // Read and print the contents of the file

    char buffer[100];

    while (fgets(buffer, sizeof buffer, fp) != NULL) {

        fputs(buffer, stdout);

    }

    // Close the file

    fclose(fp);

    return 0;

}

This program opens a file called test.txt for writing and writes some text to it. It then closes the file and reopens it for reading. It reads the contents of the file line by line and prints them to the standard output. Finally, it closes the file.

Here is an example of the output of this program:

Hello, world!
This is a test.