这是我的代码:
a = \
'''def fun():\n
print 'bbb'
'''
eval(a)
fun()
但它显示错误:
Traceback (most recent call last):
File "c.py", line 8, in <module>
eval(a)
File "<string>", line 1
def fun():
^
SyntaxError: invalid syntax
那我该怎么办
谢谢
>>> b = []
>>> c = '1234'
>>> b += c
>>> b
['1', '2', '3', '4']
>>>
这里发生了什么？这应该不行,对吗？还是我错过了一些明显的东西？
>>> b = []
>>> c = '1234'
>>> b + c
Traceback (most recent call last):
File "<pyshell#7>", line 1, in <module>
b + c
TypeError: can only concatenate list (not "str") to list
>>>
然后a += b 并不总是等同于a = a + b？
我对Python很陌生,让我对我的问题感到愤怒的是我觉得它很简单.我在第8行继续收到错误.我只是希望这个程序能够获取用户输入的数字并打印出最大的数字最小的,如果它们输入负1,我希望它取消循环.
'int' object is not iterable 是错误.
print "Welcome to The Number Input Program."
number = int(raw_input("Please enter a number: "))
while (number != int(-1)):
number = int(raw_input("Please enter a number: "))
high = max(number)
low = min(number)
print "The highest number entered was ", high, ".\n"
print "The lowest number entered was ", low, ".\n"
raw_input("\n\nPress the enter key to exit.")
1) sudo dpkg -i mysql-connector-python_1.0.12-1ubuntu12.04_all.deb
2) sudo dpkg -i mysql-utilities_1.3.5-1debian6.0_all.deb
(Reading database ... 50871 files and directories currently installed.)
Preparing to replace mysql-utilities 1.3.5 (using mysql-utilities_1.3.5-1debian6.0_all.deb) ...
Unpacking replacement mysql-utilities ...
postrm script for mysql-utilities
foundpython2.7
/opt/bitnami/python/lib/python2.7/site-packages
Setting up mysql-utilities (1.3.5) ...
postinst script for mysql-utilities
python2.7
found
python2.7
/opt/bitnami/python/lib/python2.7/site-packages
Processing triggers for man-db ...
(将在工作时提供参数)
3)尝试运行mysqlrplcheck:
$ mysqlrplcheck
Traceback (most recent call last):
File "./mysqlrplcheck", line 38, in <module>
from mysql.utilities.common.server import check_hostname_alias
File "/opt/bitnami/python/lib/python2.7/site-packages/mysql/utilities/common/server.py", line 29, in <module> …在 Python 中，异常是类并且是这样的。例如：OSError。
但是，也有一些例外，例如socket 模块中的例外，它们以小写形式命名。例如：socket.timeout，socket.error。
为什么是这样？
a='1234;5'
print a.index('s')
错误是:
> "D:\Python25\pythonw.exe" "D:\zjm_code\kml\a.py"
Traceback (most recent call last):
File "D:\zjm_code\kml\a.py", line 4, in <module>
print a.index('s')
ValueError: substring not found
谢谢
我创建了一个类:
class A:
aList = []
现在我有实例化这个类的函数,并将项添加到aList中.
注意:有2个项目
for item in items:
a = A();
a.aList.append(item);
我发现第一个A和第二个A对象在其aList中具有相同数量的项目.我希望第一个A对象将在其列表中具有第一个项目,第二个A对象将在其aList中具有第二个项目.
有谁能解释这是怎么发生的？
PS:
我设法通过在构造函数中移动aList来解决这个问题:
def __init__(self):
self.aList = [];
但我仍然对这种行为感到好奇
这真让我抓狂.
我的Python 2.5,并从可用的.exe的MySQL的Python-1.2.3 这里在Vista上安装.
我.php过去几周一直在制作网页并且连接正常,以便在我的浏览器中测试它们.
$dbcnx=@mysql_connect("localhost", "root", "mypassword")
我也一直在使用mysql命令行
mysql.exe -uroot -pmypassword just fine.
但是,当我尝试使用MySQLdb时
conn = MySQLdb.connect(host = "localhost", user = "root", passwd = "mypassword")
我明白了
OperationalError: (2003, "Can't connect to MySQL server on 'localhost' (10061)")
我已经检查过MySQL在服务中运行.我在my.ini中检查了我的MySQL配置,它在port = 3306上运行.我甚至卸载并重新安装了MySQL 5.1.我在谷歌上阅读了几页连接问题和答案,但没有任何结果.它一定是我忽略的简单,但有没有人有更多的想法？
我有一个项目,我有一个matlab代码,我必须运行'Django.我尝试安装Mlabwrap ..但是它给了我以下错误.
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "mlabwrap.py", line 188, in <module>
import mlabraw
ImportError: No module named mlabraw
我也试过ompc(http://ompc.juricap.com/)但是在添加路径之后......它给了我一个错误......
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "C:\Python27\lib\ihooks.py", line 407, in import_module
q, tail = self.find_head_package(parent, str(name))
File "C:\Python27\lib\ihooks.py", line 479, in find_head_packag
raise ImportError, "No module named '%s'" % qname
ImportError: No module named 'addpath'
def _is_dev_mode():
# quick hack to check if the program is running in dev mode.
# if 'has_key' in os.environ
if os.environ.has_key('SERVER_SOFTWARE') \
or os.environ.has_key('PHP_FCGI_CHILDREN') \
or 'fcgi' in sys.argv or 'fastcgi' in sys.argv \
or 'mod_wsgi' in sys.argv:
return False
return True
在上面的代码中显示以下错误
if os.environ.has_key('SERVER_SOFTWARE') \
AttributeError: '_Environ' object has no attribute 'has_key'