#include #include #include char *toLower(const char *str); int main(void) { char str[]="HELLO, WORLD", *strp; printf("Before toLower (%s)\n", str); strp = toLower(str); printf("After toLower (%s)\n", strp); return 0; } char *toLower(const char *str) { char *retp = (char *)malloc(strlen(str)), *retp0; retp0 = retp; while(*str) { if ( 'A' <= *str && *str <= 'Z' ) { *retp += 0x20 + *str; } else { *retp = *str; } retp++; str++; } return retp0; }