Question

我正在尝试编写一个程序，逐行读取一个名为“all_years.txt”的文件（全年），并计算一年是否是闰年。如果是这样，我想把那一年写成一个空的名为“leap_years.txt”的文件。

这是我到目前为止的代码，我无法想出这个。真诚地让我疯狂。我对编程不是很有经验，所以我很欣赏这一部分。

# calculation function
def leapYear(year):
    """ Calculates whether a year is or isn't a leap year. """
    return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)

# main function
def main():
    try:
        file = open("all_years.txt", "r")
        lines = file.readlines()
        file.close()

        for line in lines:
            if leapYear(line):
                file2 = open("leap_years.txt", "w")
                file2.write(line)
                file2.close()
    except ValueError as e:
        print(e)

main()

Answer 1

我建议您保持两个文件都打开并逐行读取输入文件。您需要使用正则表达式尝试从行中提取数字。在这种情况下，它只提取它找到的第一个数字，所以如果一行中有多个数字，你需要考虑该怎么做：

import re

def leapYear(year):
    """ Calculates whether a year is or isn't a leap year. """
    return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)        

with open('all_years.txt') as f_input, open('leap_years.txt', 'w') as f_output:
    for line in f_input:
        year = re.search(r'\b(\d+)\b', line)

        if year and leapYear(int(year.group(1))):
            f_output.write(line)

如果all_years.txt包含：

2001 
2002 
2010 
1900 
1904 World's Fair 19ol 
1946 
1984 
2000 
Year 2004 is a leap year

你会得到leap_years.txt包含：

1904 World's Fair 19ol 
1984 
2000 
Year 2004 is a leap year

Answer 2

修改以下行

file2 = open("leap_years.txt", "w")

到

file2 = open("leap_years.txt", "a")

当你使用＆＃34; w＆＃34;时，它会每次都创建一个新文件。

Answer 3

# calculation function
def leapYear(year):
    """ Calculates whether a year is or isn't a leap year. """
    year = int(year)
    return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)

# main function
def main():
    try:
        file = open("all_years.txt", "r")
        lines = file.readlines()
        file.close()

        file2 = open("leap_years.txt", "w")

        for line in lines:
            if line.isdigit():
                if leapYear(line):
                    file2.write(line)
        file2.close()
    except ValueError as e:
        print(e)

main()

将文本从一个文件传输到另一个文件 - Python

3 个答案: