Also as the name says, implicitly typed local variable, you cannot use var for field declaration or constant variables, therefore following declarations will both produce a compiler error.

故名思意，“隐式类型局部变量”将无法用于域变量或常量的声明中，否则将导致编译错误。

youdao

This means that the value of a local constant is undefined until the constant declaration statement is reached and that a local variable is undefined until the variable is assigned to in the function.

这就意味着在到达常数声明语句前局部常数值是未定义的，在函数中分配变量前局部变量是未定义的。

youdao