c language append line to file

To append a line to a file in C, you can follow these steps:

1. Open the file in append mode using the fopen() function with the "a" mode specifier.
2. Check if the file was opened successfully by comparing the file pointer returned by fopen() to NULL.
3. Use the fprintf() function to write the line to the file. Pass the file pointer, followed by the line you want to append, as arguments to fprintf().
4. Close the file using the fclose() function to release the resources associated with it.

Here is an example code snippet that demonstrates appending a line to a file in C:

#include <stdio.h>

int main() {
    FILE *file;
    char line[100];

    // Open the file in append mode
    file = fopen("filename.txt", "a");

    // Check if the file was opened successfully
    if (file == NULL) {
        printf("Unable to open the file.\n");
        return 1;
    }

    // Get the line from the user
    printf("Enter the line to append: ");
    fgets(line, sizeof(line), stdin);

    // Append the line to the file
    fprintf(file, "%s", line);

    // Close the file
    fclose(file);

    return 0;
}

In this example, the program prompts the user to enter a line, and then it appends that line to the file named "filename.txt". You can replace "filename.txt" with the actual path and name of the file you want to append to.