#include int main() {      int num= 0,nn=0; printf("Type data including a number and press \"Enter\"\n"); char ch = getchar(); while (ch  '9' && ch!='-' ) {     ch= getchar (); } while (ch >= '0' && ch <= '9' || ch=='-') {      num = num * 10 + ch - '0';          if (ch=='-')  {    nn=num;                   num=0; }ch = getchar();" } printf("Number is %d,negative number is -%d \n", num,nn);}用它读取负数时还是显示正数，复数显示-0，请问这是怎么回事？