1. 3位整数逆序
num = input("请输入一个三位整数:")
print(num[::-1])
2. if - else 练习
sex = input('请输入您的性别(F 或 M): ')
age = int(input("请输入您的年龄: "))
if sex == "M":
if age < 30:
print('young')
elif age <= 36:
print('marriageable age')
else:
print('old')
elif sex == 'F':
if age < 25:
print('young')
elif age <= 30:
print('marriageable age')
else:
print('old')
else:
print('wrong')
3. if-else 和 数学计算 练习
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my_str = input("What's the temperature? ")
if my_str[-1] in ['F', 'f']:
C = round((eval(my_str[0:-1]) - 32) / 1.8, 1)
print(f"The converted temperature is {C}C.")
elif my_str[-1] in ['C', 'c']:
F = round(1.8 * eval(my_str[0:-1]) + 32, 1)
print(f"The converted temperature is {F}F.")
else:
print("input error my dear.")
4. 循环: 文件读写
with open("movie.txt") as f_in:
with open("out.txt") as f_out:
for line in f_in:
# 假设每行数据, 分割符是 ','
line_list = line.split(',')
# 时长 Lasting 是最后一列
if line_list[-1] < 90:
# 将该行序号写到 out.txt
f_out.write(str(line_list[0]))
5.循环练习: 亲密数
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x = int(input("请输入一个正整数: "))
for a in range(2, x):
b = 0
for i in range(1, a):
if a % i == 0:
b += i
r = 0
for j in range(1, b):
if b % j == 0:
r += j
if r == a and a < b:
print(a, b)
6.循环: 逻辑判断
n = int(input('请输入最大兵力人数: '))
for i in range(n + 1):
if (i % 3 == 2) and (i % 5 == 1) and (i % 7 == 0):
print(i, end=' ')
7.列表推导式
num = int(input("请输入一个 1-100 间的整数: "))
print([i for i in range(1, num + 1) if i % 2 != 0])
8.正则表达式
# 匹配: 首字母为 '数字或下划线, 其余字母为 字母,数字,下划线'
import re
my_str = input("请输入您将要注册的用户名: ")
ret = re.match(r"[a-z_]?[a-zds_]*", my_str)
print(ret.group())
print(True) if ret else print(False)
9.字典按值排序
import operator
int(input("输入您要处理的整数个数: "))
num_lst = list(map(int, input("请在一行输入, 两两间用 空格 隔开").split()))
my_dict = {}
for num in num_lst:
if num not in my_dict:
my_dict[num] = 1
else:
my_dict[num] += 1
items = sorted(my_dict.items(), key=operator.itemgetter(1), reverse=True)
for i, j in items:
print(str(i) + ' ' + str(j))