Python 3 File readline()用法及代碼示例

描述

方法readline()從文件中讀取一整行。尾隨換行符保留在字符串中。如果 size 參數存在且非負，則它是包括尾隨換行符在內的最大字節數，並且可能會返回不完整的行。

僅當立即遇到 EOF 時才返回空字符串。

用法

以下是語法readline()方法≫

fileObject.readline( size );

參數

size─ 這是要從文件中讀取的字節數。

返回值

此方法返回從文件中讀取的行。

示例

下麵的例子展示了 readline() 方法的用法。

Assuming that 'foo.txt' file contains following text:
This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line

#!/usr/bin/python3

# Open a file
fo = open("foo.txt", "r+")
print ("Name of the file:", fo.name)

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

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

# Close opened file
fo.close()

結果

當我們運行上麵的程序時，它會產生以下結果——

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

Read Line:This