Python稳基修炼的经典案例13（计算机二级、初学者必会的字符文件处理）

1、统计基础中文字符

• 题：给定基础中文字符的unicode编码范围为｛0x4e00, 0x9fa5｝，统计文本文件中存在多少的基础中文字符及其对应的次数

fi = open("a.txt", 'r', encoding='gbk')
fo = open("c.txt", 'w', encoding='gbk')
txt = fi.read()
d = {}
for c in txt:
    if 0x4e00 <= ord(c) <= 0x9fa5:
        d[c] = d.get(c, 0) + 1
        ls = []
for key in d:
    ls.append("{}(0x{:x}):{}".format(key, ord(key), d[key]))
fo.write("，".join(ls))
fi.close()
fo.close()

2、中文版凯撒加密

s = input("请输入明文：")
d = {}
for c in [0x4e00, 0x9fa5]:
    for i in range(20902):
        d[chr(i+c)] = chr((i+10451)%20902+c)
print("凯撒加密后的文字：" + " ".join([d.get(c, c) for c in s]))

3、提取网页链接，即“href=”后面的的链接

fi = open("sweb.html", 'r', encoding='utf-8')
fo = open("text-urls.txt", 'w', encoding='utf-8')
txt = fi.read()
ls = txt.split(" ")
urls = []
for item in ls:
    if item[:5] == "href=" and item[6:13] == "http://":
        urls.append(item[6:-1])
        for item in urls:
            fo.write(item+'\n')
fi.close()
fo.close()