我们有可能会写出或者遇到类似这种代码：
C/C++switch (expr1)
{
case label11:
switch (expr2)
{
case label21:
// do something
break;
case label22:
// do something
break;
default:
// do something
break;
}
break;
case label12:
switch (expr2)
{
case label21:
// do something
break;
case label22:
// do something
break;
default:
// do something
break;
}
break;
case label13:
switch (expr2)
{
case label21:
// do something
break;
case label22:
// do something
break;
default:
// do something
break;
}
break;
default:
// do something
break;
}
这时能够考虑将两个嵌套的switch-case语句通过以下的方式转换为一个switch-case语句：
示比例如以下：
C/C++new_expr = expr1 << expr2_max_bit + expr2;
switch (new_expr)
{
case label1:
// do something
break;
case label2:
// do something
break;
case label3:
// do something
break;
case label4:
// do something
break;
case label5:
// do something
break;
case label6:
// do something
break;
default:
// do something
break;
}