注意小心边界值,字母还要考虑大写
int main() { char a; int Letters = 0, Digits = 0, Others = 0; while ((a = getchar()) != '?') { if ((a >= '0') && (a <= '9')) Digits++; else if ((a >= 'a') && (a <= 'z')) Letters++; else if ((a >= 'A') && (a <= 'Z')) Letters++; else Others++; } printf("Letters=%d\n", Letters); printf("Digits=%d\n", Digits); printf("Others=%d\n", Others); return 0; }