readline()方法從文件中讀取一整行。尾部的換行符保持在字符串中。如果大小參數且非負，那么一個最大字節數，包括結尾的換行和不完整的行可能會返回。

遇到EOF時立即返回一個空字符串。
語法

以下是readline()方法的語法：

fileObject.readline( size );

參數

返回值

此方法返回從文件中讀取的行。
例子

下面的例子顯示了readline()方法的使用。

#!/usr/bin/python# Open a filefo = open("foo.txt", "rw+")print "Name of the file: ", fo.name# Assuming file has following 5 lines# This is 1st line# This is 2nd line# This is 3rd line# This is 4th line# This is 5th lineline = fo.readline()print "Read Line: %s" % (line)line = fo.readline(5)print "Read Line: %s" % (line)# Close opend filefo.close()

當我們運行上面的程序，它會產生以下結果：

Name of the file: foo.txtRead Line: This is 1st lineRead Line: This