python之全局变量的测试

来源：http://andylin02.iteye.com/blog/841604

结论：python的全局变量：int string， list， dic(map) 如果存在global就能够修改它的值。而不管这个global是否是存在于if中，也不管这个if是否能够执行到。

但是，如果没有

Python代码


if bGlobal:

global g_strVal;

int string 将会报错。而list dic(map)是ok的。

Python代码


#!/usr/bin/dev python

import sys

import os

g_nVal = 0;

g_strVal = "aaaa";

g_map = {

"aaa" : "111",

"bbb" : "222",

"ccc" : "333",

"ddd" : "444"

}

g_ls = ['a', 'b', 'c']

def FixInt(bGlobal = False):

if bGlobal:

global g_nVal;

g_nVal = g_nVal + 1;

def FixString(bGlobal = False):

if bGlobal:

global g_strVal;

#fix string value

g_strVal = g_strVal + 'b';

def FixMap(bGlobal = False):

if bGlobal:

global g_map;

#fix map value

g_map['aaa'] = 'aaa__' + g_strVal;

g_map['bbb'] = 'bbb__' + g_strVal;

g_map['ccc'] = 'ccc__' + g_strVal;

g_map['ddd'] = 'ddd__' + g_strVal;

def FixList(bGlobal = False):

if bGlobal:

global g_ls;

g_ls.append('1');

def PrintVal(strInfo):

if strInfo:

print("==== %s =====" %strInfo);

print("int value:%d" %g_nVal);

print("string value:%s" %g_strVal);

print("map value:%s" %g_map);

print("list value:%s" %g_ls);

print("\n\n");

if "__main__" == __name__:

PrintVal("The orgin vlaue");

FixInt();

FixString();

FixMap();

FixList();

PrintVal("print all bGlobal = False vlaue");

FixInt(True);

FixString(True);

FixMap(True);

FixList(True);

PrintVal("print all bGlobal = True vlaue");

结果：

==== The orgin vlaue =====
int value:0
string value:aaaa
map value:{'aaa': '111', 'bbb': '222', 'ccc': '333', 'ddd': '444'}
list value:['a', 'b', 'c']

g_nVal src:0
g_nVal dst:1
==== print all bGlobal = False value =====
int value:1
string value:aaaab
map value:{'aaa': 'aaa__aaaab', 'bbb': 'bbb__aaaab', 'ccc': 'ccc__aaaab', 'ddd': 'ddd__aaaab'}
list value:['a', 'b', 'c', '1']

g_nVal src:1
g_nVal dst:2
==== print all bGlobal = True value =====
int value:2
string value:aaaabb
map value:{'aaa': 'aaa__aaaabb', 'bbb': 'bbb__aaaabb', 'ccc': 'ccc__aaaabb', 'ddd': 'ddd__aaaabb'}
list value:['a', 'b', 'c', '1', '1']