Thread: Write to file using struct

While programming with the struct data type, I have a .txt that I wish to write to and I am unable to do so. Below I showcase my code, the problem is the contents of my file become overridden whereas I wish to simply add onto it.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


// a struct to read and write
struct person
{
    int id;
    char fname[20];
    char lname[20];
};


int main ()
{
    FILE *outfile;


    // open file for writing
    outfile = fopen ("person.txt", "w");
    if (outfile == NULL)
    {
        fprintf(stderr, "\nError opened file\n");
        exit (1);
    }


    struct person input1 = {1, "rohan", "sharma"};
    struct person input2 = {2, "mahendra", "dhoni"};


    // write struct to file
    //fwrite (&input1, sizeof(struct person), 1, outfile);
    //fwrite (&input2, sizeof(struct person), 1, outfile);


    //Why does the above erase the contents already in my file
    //I want to keep them and to add the above lines to the file


    if(&fwrite != 0)
        printf("contents to file written successfully !\n");
    else
        printf("error writing file !\n");


    // close file
    fclose (outfile);


    return 0;
}