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

if bGlobal:
       global g_strVal;

int string 将会报错。而list dic(map)是ok的。

 

#!/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("

");

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']