简单介绍Python中的readline()方法的使用

readline()方法从文件中读取一整行。尾部的换行符保持在字符串中。如果大小参数且非负，那么一个最大字节数，包括结尾的换行和不完整的行可能会返回。

遇到EOF时立即返回一个空字符串。
语法

以下是readline()方法的语法：

    fileObject.readline( size );

参数

• size -- 这是可以从文件中读取的字节数。

返回值

此方法返回从文件中读取的行。
例子

下面的例子显示了readline()方法的使用。

    #!/usr/bin/python

    # Open a file
    fo = 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 line

    line = fo.readline()
    print "Read Line: %s" % (line)

    line = fo.readline(5)
    print "Read Line: %s" % (line)

    # Close opend file
    fo.close()

当我们运行上面的程序，它会产生以下结果：

    Name of the file: foo.txt
    Read Line: This is 1st line

    Read Line: This