file.readline([size])
描述 (Description)
readline()方法从文件中读取整行。 尾随换行符保留在字符串中。 如果size参数存在且非负数，则它是包含尾随换行符的最大字节数，并且可能返回不完整的行。
仅在立即遇到EOF时才返回空字符串。
语法 (Syntax)
以下是readline()方法的语法 -
fileObject.readline( size );
参数 (Parameters)
size - 这是从文件中读取的字节数。
返回值 (Return Value)
此方法返回从文件中读取的行。
例子 (Example)
以下示例显示了readline（）方法的用法。
This is 1st line
This is 2nd line
This is 3rd line
This is 4th line
This is 5th line
#!/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时，它产生以下结果 -
Name of the file: foo.txt
Read Line: Python is a great language.
Read Line: Yeah
