C语言 GOTO 你不知道的事情
错误Code
#include <stdio.h>
int main()
{
int a=1,b=2;
goto End;
int c[b];
End:
return 0;
}
编译器报错内容
In function 'main':[Error] jump into scope of identifier with variably modified type
[Note] label 'End' defined here
[Note] 'c' declared here
为什么会出现
根据C11标准:
A goto statement is not allowed to jump past any declarations of objects with variably modified types. A jump within the scope, however, is permitted.
也就是说goto语句与“标签”之间的code不允许有可变长数组的声明语句。因为goto是无条件跳转语句,需要在编译时确定地址,如果可变长数组夹在其中,则编译器无法确定地址。
以下code都正确
#include <stdio.h>
int main()
{
goto End;
int a=1,b=2;
int c[2];
End:
return 0;
}
怎么解决
将可变长数组的定义移动到“goto-tag”范围之外
#include <stdio.h>
int main()
{
int a=1,b=2;
int c[a];
Begin:
goto End;
End:
return 0;
}
喜欢就一键三连吧!!!