python 异常

 

try：

　　....

except   :

　　.....

else:

　　....

除数不能为0

try:
    print(5/0)
except ZeroDivisionError:
    print("You can't divide by zero!")

 

除数不能为0的 异常处理代码块，，，，把可能要出错的步骤放到try中 进行处理

print("Give me two numbers, and I'll divide them.")
print("Enter 'q' to quit.")

while True:
    first_number = input("\nFirst number: ")
    if first_number == 'q':
        break
    second_number = input("Second number: ")
    if second_number == 'q':
        break
    try:
        answer = int(first_number) / int(second_number)
    except ZeroDivisionError:
        print("you can't by zero")
    else:
        print(answer)

 

 

计算这个文件中大概有多少个单词

这里将文件的打开动作房贷了try语句块中，如果发现文件找不到异常，就会执行   except FileNotFoundError  这里

filename = 'programming_poll.txt'

try:
    with open(filename, encoding='utf-8') as f:
        contents = f.read()
except FileNotFoundError:
    print(f"Sorry, the file {filename} does not exist.")
else:
    # 计算该文件大致包含多少个单词。
    words = contents.split()
    num_words = len(words) 
    print(f"The file {filename} has about {num_words} words.")