How to copy data from one file to another file in C Language?

 In C language, you can copy data from one file to another using the following steps:

1. Open the source file in read mode and the destination file in write mode using the fopen() function.
2. Check if both files were opened successfully.
3. Read data from the source file using the fread() function and write it to the destination file using the fwrite() function.
4. Repeat step 3 until the end of the source file is reached.
5. Close both files using the fclose() function.

Here is an example program that copies data from one file to another:

c
#include <stdio.h>

int main() {
    FILE *source_file, *dest_file;
    char ch;

    source_file = fopen("source.txt", "r");

    if (source_file == NULL) {
        printf("Error opening source file.");
        return 1;
    }

    dest_file = fopen("destination.txt", "w");

    if (dest_file == NULL) {
        printf("Error opening destination file.");
        return 1;
    }

    while ((ch = fgetc(source_file)) != EOF) {
        fputc(ch, dest_file);
    }

    printf("File copied successfully.");

    fclose(source_file);
    fclose(dest_file);

    return 0;
}

In this program, the source file is opened in read mode and the destination file is opened in write mode using the fopen() function. The program checks if both files were opened successfully. The while loop reads each character from the source file using the fgetc() function and writes it to the destination file using the fputc() function. Finally, both files are closed using the fclose() function.