统计一个文件中出现字符'a'的次数

# -*- coding: utf-8 -*-
#python 27
#xiaodeng
#统计一个文件中出现字符'a'的次数
#http://www.cnblogs.com/hongten/p/hongten_python_count.html

import os
number=0
def getNumber(filePath,c):
    'c---->the word numbers'
    #统计一个文件中出现字符'a'的次数
    if os.path.exists(filePath):
        global number
        with open(filePath,'r') as fp:
            for line in fp:
                countNumber=line.count(c)
                number=number+countNumber
    else:
        print 'the path:[{}] is not exist!'.format(filePath)

    #返回number数目
    #return number 

if __name__=='__main__':
    file_path='out.txt'
    print getNumber(file_path,'xiaodeng')
    #number为全局变量，可以直接进行输出操作
    print number

#将上面的案例进行一些修改操作：
print '**'*20
def getNumber(filePath,c):
    import os
    if os.path.exists(filePath):
        number=0
        with open(filePath,'r') as fp:
            for line in fp:
                countNumber=line.count(c)
                number=number+countNumber
        return number
    else:
        print 'the path:[{}] is not exist!'.format(filePath)

if __name__=='__main__':
    file_path='out.txt'
    print getNumber(file_path,'xiaodeng')