python变量不能以数字打头详解
在编写python函数时，无意中发现一个问题：python中的变量不能以数字打头，以下函数中定义了一个变量3_num_varchar，执行时报错。
函数如下：
defdatabase_feild_varchar_trans(in_feild):
'''
transferthefeildifvarcharthen3timeslangelsenotransfer
'''
feild_split=in_feild.split('')
is_varchar=feild_split[1].find('VARCHAR')
ifis_varchar>=0:
num_varchar=feild_split[1].replace('VARCHAR','').replace('(','').replace(')','')
print(num_varchar)
3_num_varchar=num_varchar*3
feild_split[1]=feild_split[1].replace(str(num_varchar),str(3_num_varchar))
returnfeild_split
else:
print('Thefeildtypeisnotvarchar')
returnfeild_split
报错信息如下：
>>>runfile('E:/procedure/python/projects/others/table_test.py',wdir='E:/procedure/python/projects/others')
Traceback(mostrecentcalllast):
File"<stdin>",line1,in<module>
File"D:\Python33\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py",line699,inrunfile
execfile(filename,namespace)
File"D:\Python33\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py",line88,inexecfile
exec(compile(open(filename,'rb').read(),filename,'exec'),namespace)
File"E:/procedure/python/projects/others/table_test.py",line20
3_num_varchar=int(num_varchar)*3
^
SyntaxError:invalidsyntax
将变量3_num_varchar改为num_varchar_3，运行成功，程序改为如下：
importos
importsys
str1='aaavarchar(10)'
defdatabase_feild_varchar_trans(in_feild):
'''
transferthefeildifvarcharthen3timeslangelsenotransfer
'''
feild_split=in_feild.split('')
is_varchar=feild_split[1].find('VARCHAR')
ifis_varchar>=0:
num_varchar=feild_split[1].replace('VARCHAR','').replace('(','').replace(')','')
print(num_varchar)
num_varchar_3=num_varchar*3
feild_split[1]=feild_split[1].replace(str(num_varchar),str(num_varchar_3))
returnfeild_split
else:
print('Thefeildtypeisnotvarchar')
returnfeild_split
print(database_feild_varchar_trans(str1))
运行结果：
>>>runfile('E:/procedure/python/projects/others/table_test.py',wdir='E:/procedure/python/projects/others')
Thefeildtypeisnotvarchar
['aaa','varchar(10)']
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