代码部分
int read() {
int x; char ch; bool minus = false;
while (ch = getchar(), (ch<'0' || ch>'9') && ch != '-');
if (ch == '-') {
minus = true;
ch = getchar();
}
x = ch - 48;
while (ch = getchar(), ch <= '9'&&ch >= '0')x = x * 10 + ch - 48;
return minus ? -x : x;
}
怎么理解while这部分