python变量不能以数字打头详解

发布时间：2020-12-16 20:31:21 所属栏目：Python 来源：网络整理

导读：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： def database_feild_varchar_trans(in_feild): ''' transfer the feild if varchar then 3times lang else no tra

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：

def database_feild_varchar_trans(in_feild):
  '''
  transfer the feild if varchar then 3times lang else no transfer
  '''
  feild_split = in_feild.split(' ')
  is_varchar = feild_split[1].find('VARCHAR')
  if is_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))
    return feild_split
  else:
    print ('The feild type is not varchar')
    return feild_split

报错信息如下：

>>> runfile('E:/procedure/python/projects/others/table_test.py',wdir='E:/procedure/python/projects/others')
Traceback (most recent call last):
 File "<stdin>",line 1,in <module>
 File "D:Python33libsite-packagesspyderlibwidgetsexternalshellsitecustomize.py",line 699,in runfile
  execfile(filename,namespace)
 File "D:Python33libsite-packagesspyderlibwidgetsexternalshellsitecustomize.py",line 88,in execfile
  exec(compile(open(filename,'rb').read(),filename,'exec'),namespace)
 File "E:/procedure/python/projects/others/table_test.py",line 20
  3_num_varchar = int(num_varchar)*3
        ^
SyntaxError: invalid syntax

将变量3_num_varchar改为num_varchar_3，运行成功，程序改为如下：

import os
import sys
str1='aaa varchar(10)'

def database_feild_varchar_trans(in_feild):
  '''
  transfer the feild if varchar then 3times lang else no transfer
  '''
  feild_split = in_feild.split(' ')
  is_varchar = feild_split[1].find('VARCHAR')
  if is_varchar >= 0 :
    num_varchar = feild_split[1].replace('VARCHAR','') 
    print (num_varchar)
    num_varchar_3 = num_varchar*3
    feild_split[1] = feild_split[1].replace(str(num_varchar),str(num_varchar_3))
    return feild_split
  else:
    print ('The feild type is not varchar')
    return feild_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')
The feild type is not varchar
['aaa','varchar(10)']

以上这篇python变量不能以数字打头详解就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持编程小技巧。

（编辑：李大同）

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