//en.cppreference.com/w/c/program/abort.html
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
FILE *fp = fopen("data.txt","r");
if (fp == NULL) {
fprintf(stderr, "error opening file data.txt in function main()\n");
abort();
}
/* Normal processing continues here. */
fclose(fp);
printf("Normal Return\n");
return 0;
}