#include <stdio.h> #include <stdint.h> #include <string.h> int main(void) { char text[8] = "Hell^23o"; size_t len = strlen(text); uint64_t mask = 0; for (size_t i = 0; i < 8; ++i) { if ((text[i] >= 'a' && text[i] <= 'z') || (text[i] >= 'A' && text[i] <= 'Z')) mask |= (size_t)0x20 << (i * 8); } *(uint64_t *)&text &= ~mask; printf("Upper: %.8s\n", text); *(uint64_t *)&text |= mask; if (len < 8) { text[len] = 0; } printf("Lower: %.8s\n", text); return 0; }