//en.cppreference.com/w/c/io/rename.html
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
FILE* fp = fopen("from.txt", "w"); // create file "from.txt"
if (!fp)
{
perror("from.txt");
return EXIT_FAILURE;
}
fputc('a', fp); // write to "from.txt"
fclose(fp);
int rc = rename("from.txt", "to.txt");
if (rc)
{
perror("rename");
return EXIT_FAILURE;
}
fp = fopen("to.txt", "r");
if(!fp)
{
perror("to.txt");
return EXIT_FAILURE;
}
printf("%c\n", fgetc(fp)); // read from "to.txt"
fclose(fp);
return EXIT_SUCCESS;
}