Python命令行参数分号循环错误

Question

我正在尝试,python -mtimeit所以我把python -mtimeit "n = 0; while n < 10: pass" 然后出现了无效的语法错误.与分号和循环相同.

但是,当我尝试分号并单独循环时.两者都很好.

python -c "for i in range(10): print(n)"  
python -c "n = 1; n = 2; print(n)"

为什么会如此？如何在timeit中测试while循环？非常感谢你!

Answer 1

while,for之前不能有分号,它们需要在一条线上.如果你看一下Python语法:

compound_stmt ::=  if_stmt
                   | while_stmt
                   | for_stmt
                   | try_stmt
                   | with_stmt
                   | funcdef
                   | classdef
                   | decorated
suite         ::=  stmt_list NEWLINE | NEWLINE INDENT statement+ DEDENT
statement     ::=  stmt_list NEWLINE | compound_stmt
stmt_list     ::=  simple_stmt (";" simple_stmt)* [";"]

你会看到那些声明只compound_stmt需要一行一行.可以用分号分隔的唯一语句是simple_stmtgroup:

simple_stmt ::=  expression_stmt
                 | assert_stmt
                 | assignment_stmt
                 | augmented_assignment_stmt
                 | pass_stmt
                 | del_stmt
                 | print_stmt
                 | return_stmt
                 | yield_stmt
                 | raise_stmt
                 | break_stmt
                 | continue_stmt
                 | import_stmt
                 | global_stmt
                 | exec_stmt