python全栈开发《29.字符串格式化的三种方式之格式化函数-format、新格式化方案：f-strings》

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发布于 2024-10-15 10:43:16

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文章被收录于专栏：清菡软件测试清菡软件测试

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代码可运行

1.字符串格式化函数-format

1)string.format函数用来格式化字符串。
2)使用format的字符串主体使用{}大括号来替代格式符。
3)完整用法：string.format(data,data,data...)

print('hello {0},今天看起来气色{1}'.format('小编','不错'))

运行结果：

/Users/llq/PycharmProjects/pythonlearn/pythonlearn/.venv/bin/python /Users/llq/PycharmProjects/pythonlearn/pythonlearn1/1.py 
hello 小编,今天看起来气色不错

进程已结束，退出代码为 0

0和1分别代表了format中的顺序。0代表小编，1代表不错。

不需要在{}中添加位置的数字：0，1这样的，添加了位置数字也是没有错的：

例1:

# coding:utf-8

info = 'my name is %s,my age is %s'

name_01 = '小编'
age_01 = 10
name_02 = 'dewei'
age_02 = 33
print(info % (name_01,age_01))
print(info % (name_02,age_02))

message = '您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值'
print(message % ('星期一',123456789))
print(message % (1234567,'星期2'))
print(message)

books =['python','django','flask']
info_2 = 'my name is %s,my age is %s,my book is %s'
print(info_2 % (name_01,age_01,books))

dict_01 = {'a':'a','b':'b'}
print('dict is %s' % dict_01)

info_3  = 'my name is {},my age is {}'
print(info_3.format(name_02,age_02))

运行结果：

/Users/llq/PycharmProjects/pythonlearn/pythonlearn/.venv/bin/python /Users/llq/PycharmProjects/pythonlearn/pythonlearn1/format.py 
my name is 小编,my age is 10
my name is dewei,my age is 33
您好，今天是星期一，您的手机号码：123456789 已经欠费了，请尽快充值
您好，今天是1234567，您的手机号码：星期2 已经欠费了，请尽快充值
您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值
my name is 小编,my age is 10,my book is ['python', 'django', 'flask']
dict is {'a': 'a', 'b': 'b'}
my name is dewei,my age is 33

进程已结束，退出代码为 0

例2:

# coding:utf-8

info = 'my name is %s,my age is %s'

name_01 = '小编'
age_01 = 10
name_02 = 'dewei'
age_02 = 33
print(info % (name_01,age_01))
print(info % (name_02,age_02))

message = '您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值'
print(message % ('星期一',123456789))
print(message % (1234567,'星期2'))
print(message)

books =['python','django','flask']
info_2 = 'my name is %s,my age is %s,my book is %s'
print(info_2 % (name_01,age_01,books))

dict_01 = {'a':'a','b':'b'}
print('dict is %s' % dict_01)

info_3  = 'my name is {0},my age is {1},my book is {2}'
print(info_3.format(name_02,age_02,books))

运行结果：

/Users/llq/PycharmProjects/pythonlearn/pythonlearn/.venv/bin/python /Users/llq/PycharmProjects/pythonlearn/pythonlearn1/format.py 
my name is 小编,my age is 10
my name is dewei,my age is 33
您好，今天是星期一，您的手机号码：123456789 已经欠费了，请尽快充值
您好，今天是1234567，您的手机号码：星期2 已经欠费了，请尽快充值
您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值
my name is 小编,my age is 10,my book is ['python', 'django', 'flask']
dict is {'a': 'a', 'b': 'b'}
my name is dewei,my age is 33,my book is ['python', 'django', 'flask']

进程已结束，退出代码为 0

如果format中的数量和格式符不一致，就会报错：

例3:

# coding:utf-8

info = 'my name is %s,my age is %s'

name_01 = '小编'
age_01 = 10
name_02 = 'dewei'
age_02 = 33
print(info % (name_01,age_01))
print(info % (name_02,age_02))

message = '您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值'
print(message % ('星期一',123456789))
print(message % (1234567,'星期2'))
print(message)

books =['python','django','flask']
info_2 = 'my name is %s,my age is %s,my book is %s'
print(info_2 % (name_01,age_01,books))

dict_01 = {'a':'a','b':'b'}
print('dict is %s' % dict_01)

info_3  = 'my name is {0},my age is {1},my book is {2}'
print(info_3.format(name_02,age_02))

运行结果：

/Users/llq/PycharmProjects/pythonlearn/pythonlearn/.venv/bin/python /Users/llq/PycharmProjects/pythonlearn/pythonlearn1/format.py 
my name is 小编,my age is 10
my name is dewei,my age is 33
您好，今天是星期一，您的手机号码：123456789 已经欠费了，请尽快充值
您好，今天是1234567，您的手机号码：星期2 已经欠费了，请尽快充值
您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值
my name is 小编,my age is 10,my book is ['python', 'django', 'flask']
dict is {'a': 'a', 'b': 'b'}
Traceback (most recent call last):
 File "/Users/llq/PycharmProjects/pythonlearn/pythonlearn1/format.py", line 25, in <module>
   print(info_3.format(name_02,age_02))
IndexError: Replacement index 2 out of range for positional args tuple

进程已结束，退出代码为 1

2.python3.6加入的新格式化方案：f-strings

定义一个变量。
字符串前加f符号。
需要格式化的位置使用{变量名}。

# coding:utf-8

info = 'my name is %s,my age is %s'

name_01 = '小编'
age_01 = 10
name_02 = 'dewei'
age_02 = 33
print(info % (name_01,age_01))
print(info % (name_02,age_02))

message = '您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值'
print(message % ('星期一',123456789))
print(message % (1234567,'星期2'))
print(message)

books =['python','django','flask']
info_2 = 'my name is %s,my age is %s,my book is %s'
print(info_2 % (name_01,age_01,books))

dict_01 = {'a':'a','b':'b'}
print('dict is %s' % dict_01)

info_3  = 'my name is {0},my age is {1},my book is {2}'
print(info_3.format(name_02,age_02,books))

info_4 =  f'my name is {name_01},my age is {age_02}'
print(info_4)

/Users/llq/PycharmProjects/pythonlearn/pythonlearn/.venv/bin/python /Users/llq/PycharmProjects/pythonlearn/pythonlearn1/format.py 
my name is 小编,my age is 10
my name is dewei,my age is 33
您好，今天是星期一，您的手机号码：123456789 已经欠费了，请尽快充值
您好，今天是1234567，您的手机号码：星期2 已经欠费了，请尽快充值
您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值
my name is 小编,my age is 10,my book is ['python', 'django', 'flask']
dict is {'a': 'a', 'b': 'b'}
my name is dewei,my age is 33,my book is ['python', 'django', 'flask']
my name is 小编,my age is 33

进程已结束，退出代码为 0

这种格式化方法，一定要提前定义好变量名，否则是无法使用的。

3.哪种格式化方法更好？

推荐使用format函数，使用format函数不需要提前定义好变量名，也比第一种方法：根据类型定义的格式化，更简单。

# coding:utf-8

info = 'my name is %s,my age is %s'

name_01 = '小编'
age_01 = 10
name_02 = 'dewei'
age_02 = 33
print(info % (name_01,age_01))
print(info % (name_02,age_02))

message = '您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值'
print(message % ('星期一',123456789))
print(message % (1234567,'星期2'))
print(message)

books =['python','django','flask']
info_2 = 'my name is %s,my age is %s,my book is %s'
print(info_2 % (name_01,age_01,books))

dict_01 = {'a':'a','b':'b'}
print('dict is %s' % dict_01)

info_3  = 'my name is {0},my age is {1},my book is {2}'
print(info_3.format(name_02,age_02,books))

info_4 =  f'my name is {name_01},my age is {age_02}'
print(info_4)

print(info_3.format('dewei',33,['python']))

运行结果：

/Users/llq/PycharmProjects/pythonlearn/pythonlearn/.venv/bin/python /Users/llq/PycharmProjects/pythonlearn/pythonlearn1/format.py 
my name is 小编,my age is 10
my name is dewei,my age is 33
您好，今天是星期一，您的手机号码：123456789 已经欠费了，请尽快充值
您好，今天是1234567，您的手机号码：星期2 已经欠费了，请尽快充值
您好，今天是%s，您的手机号码：%s 已经欠费了，请尽快充值
my name is 小编,my age is 10,my book is ['python', 'django', 'flask']
dict is {'a': 'a', 'b': 'b'}
my name is dewei,my age is 33,my book is ['python', 'django', 'flask']
my name is 小编,my age is 33
my name is dewei,my age is 33,my book is ['python']

进程已结束，退出代码为 0