我将printf和/或其他函数应用于某个字符串,从文件中读取.我想在某些条件下跳过前5个字符.现在我觉得很聪明,如果条件适用,将字符串指针增加5:
if (strlen(nav_code) == 10 ) {nav_code = 5+nav_code;}
但是编译器拒绝这个:
错误:使用数组类型赋值给表达式
我误解了什么？如何使我的想法工作 - 或者无论如何这是一个坏主意？
环境：Ubuntu 18.04.6 LTS，python 3.6.9，mysql Ver 14.14 Distrib 5.7.41
我添加的软件包： mysql-connector-python-py3 mysql-connector-python-py3-dbgsym
执行：
Python 3.6.9 (default, Mar 10 2023, 16:46:00)
[GCC 8.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import mysql.connector
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/usr/lib/python3/dist-packages/mysql/connector/__init__.py", line 32, in <module>
from .connection_cext import CMySQLConnection
File "/usr/lib/python3/dist-packages/mysql/connector/connection_cext.py", line 40, in <module>
from .abstracts import MySQLConnectionAbstract
File "/usr/lib/python3/dist-packages/mysql/connector/abstracts.py", line 33
from __future__ import annotations
^
SyntaxError: future feature annotations is …请在下面的对话框中帮忙解决很多问题:
- )为什么"subprocess.check_output(["ls"," - rt","."])"产生没有输出,但至少被接受了？
- )为什么"subprocess.check_output(["ls -rt","."])"根本不被接受？
- )最重要的是:我怎样才能在python中获取与某些正则表达式匹配的最新文件的名称？我的想法是向python提供类似"ls -rt $ REGEX | head -1"的东西,但python似乎非常不喜欢这样的方法..？
karel@suske:~/home_shared/develop/airnav_db$ python --version
Python 2.7.6
karel@suske:~/home_shared/develop/airnav_db$ python -c 'import subprocess ; subprocess.check_output(["ls -rt","."])'
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/usr/lib/python2.7/subprocess.py", line 566, in check_output
process = Popen(stdout=PIPE, *popenargs, **kwargs)
File "/usr/lib/python2.7/subprocess.py", line 710, in __init__
errread, errwrite)
File "/usr/lib/python2.7/subprocess.py", line 1327, in _execute_child
raise child_exception
OSError: [Errno 2] No such file or directory
karel@suske:~/home_shared/develop/airnav_db$ python -c 'import subprocess …