error: crosses initialization of xxx IN switch case

　　

The C++ standard says: It is possible to transfer into a block, but not in a way that bypasses declarations with initialization. A program that jumps from a point where a local variable with automatic storage duration is not in scope to a point where it is in scope is ill-formed unless the variable has POD type (3.9) and is declared without an initializer. The cases in switch are considered as a "jump". Just put all objects and variables initializations before your switch, and everything will be fine. Consider this code: switch(k){case1:int t =4;break;default:break;} It will cause a "crosses initialization" error, because it is possible to skip the initialization of t, but after that it will still be in scope, even though it was never created in the first place. Now consider this: switch(k){case1:{int t =4;}break;default:break;} Here, you will not have the error, because the variable is inside a block, and will die at the end of the block ( at the closing { ), so after that it will not be in scope in any case. To fix the first case, you just need to do: int t =0;switch(k){case1: t =4;break;default:break;}

转载于:https://www.cnblogs.com/zhangyz/articles/3145531.html