Python 计算文件中总行数

count = len(open(filepath,'rU').readlines())

count = -1
for count, line in enumerate(open(thefilepath, 'rU')):
    pass
count += 1

count = 0
thefile = open(thefilepath, 'rb')
while True:
    buffer = thefile.read(8192*1024)
    if not buffer:
        break
    count += buffer.count('\n')
thefile.close( )

import linecache

count = linecache.getline(filename,linenum)

str = linecache.getlines(filename)