python variable scope 变量作用域

python 中变量的作用域经常让我感到很迷

In Python, on the other hand, variables declared in if-statements, for-loop blocks, and while-loop blocks are not local variables, and stay in scope outside of the block. Thus we say that C++ has “block-level” scoping, while Python uses only “function-level” scoping. The brackets in the figure below illustrate the scope for some variables in equivalent C++ and Python code. Because C++ uses block-level scoping, and x and y are declared inside of blocks, we cannot access their contents outside of those blocks.