#include <stdio.h> #include <ctype.h> main() { char ch; int n=0; while((ch=getchar())!='\n') { if(ch>='0'&&ch<='9') n=n*10+ch-'0'; } printf("%d\n",n);} 程序我是知道,但有个语句不懂n=n*10+ch-'0'; 哪位能讲下?