#文件比较小

count = len(open(r"d:\lines_test.txt",'rU').readlines())

print count

#文件比较大

count = -1

for count,line in enumerate(open(r"d:\lines_test.txt",'rU')):

pass

count += 1

print count

#更好的方法

count = 0

thefile = open(r"d:\lines_test.txt",'rb')

while True:

buffer = thefile.read(1024 * 8192)

if not buffer:

break

count += buffer.count('\n')

thefile.close()

print count