why we need to check for errors while writing a file in C? [on hold]

what is the need of checking for errors in this program in line 7.

 #include <stdio.h>
    int main()
    {
       int n;
       FILE *fptr;
       fptr=fopen("C:\\program.txt","w");
       if(fptr==NULL){
          printf("Error!");   
          exit(1);             
       }
       printf("Enter n: ");
       scanf("%d",&n);
       fprintf(fptr,"%d",n);   
       fclose(fptr);
       return 0;
    }