答案:#include int main(void){char c;int blank, digit, letter, other;c = getchar();blank = digit = letter = other = 0;while(c != '\n'){if(c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z')letter ;else if(c >= '0' && c <= '9')digit ;else if(c == ' ')blank ;elseother ;c = getchar();}printf("letter = %d, blank = %d, digit = %d, other = %d\n", letter, blank, digit, other);return 0;}