/* PBXA64 handbook-style C text example: rot13_transform.
 * apply the involutive ROT13 alphabet transform twice. This source deliberately keeps every transformation visible
 * instead of hiding it behind library calls, making it useful for tracing.
 */
int main(void) {
    char s[] = "Hello"; int pass = 0, i = 0; for (pass = 0; pass < 2; ++pass) for (i = 0; s[i] != 0; ++i) { if (s[i] >= 'A' && s[i] <= 'Z') s[i] = (char)('A' + ((s[i] - 'A' + 13) % 26)); else if (s[i] >= 'a' && s[i] <= 'z') s[i] = (char)('a' + ((s[i] - 'a' + 13) % 26)); } return s[0] == 'H' ? 0 : 1;
}

/* Discussion: inspect the loop bounds, byte classification, and final return
 * value. The bounded-C frontend currently records CIR0200 for all C source;
 * this example remains a real handbook program for the public C surface once
 * that frontend gate is restored. */
