**Formatted output: The content is output according to certain format requirements. **
Before the python2.6 version, the output format of the C language was used for the% format string.
Instructions for use:
print("format string"% variable)
Use tuple format for more than 2 variables:
print("format string"% (variable 1, variable 2))
Use% placeholders to indicate the position of the variable in the string.
The value passed in should correspond to the variable of the% placeholder one by one.
Among them, %s represents a string, %d represents an integer, and %f represents a decimal (the default is to retain 6 decimal places, and %.2f retains two decimal places). When there is a formatting flag, %% needs to be used to represent a percent sign.
name='xiaoming'
age=12print("My name is %s,My age is %d"%(name,age))
# Output: My name is xiaoming,My age is 12
format is a new method for formatting strings in python2.6. Compared with the% formatting method, it has the following advantages:
Instructions for use:
print("...{index}, ... , {index}, ...".format(Value 1,Value 2))
# index{}Empty, the default value is in order
print("...{key1}, ... , {key2}, ...".format(key1=value,key2=value))
name='xiaoming'
age=12print('My name is {}, My age is {}'.format(name,age))print('My name is {0}, My age is {1}'.format(name,age))print('My name is {name}, My age is {age}'.format(name='xiaoming',age=12))
# Output: My name is xiaoming,My age is 12
1. Fill alignment
# Get the value first,Then set the padding format after the colon:{index:[Fill character][Alignment][width]}
# *<20 : Left-justified, a total of 20 characters, not enough*Number fill
print('{0:*<20}'.format('hellopython'))
# *>20 : Right justified, 20 characters in total, not enough*Number fill
print('{0:*>20}'.format('hellopython'))
# *^20 : Center display, a total of 20 characters, not enough*Number fill
print('{0:*^20}'.format('hellopython'))
Output:
hellopython******************hellopython
****hellopython*****
2. Digit and base conversion
# Keep 2 significant figures
print("{:.2f}".format(3.1415926))
# Convert to binary
print('{0:b}'.format(16))
# Convert to octal
print('{0:o}'.format(10))
# Convert to hexadecimal
print('{0:x}'.format(15))
Output
3.141000012
f
F-strings was introduced in Python 3.6, which is not only easier to use than str.format, but also more efficient.
Instructions for use
f-string is the string with "f" before it, {} directly uses variables, expressions, etc.
name='xiaoming'
age=12
#{} Use variables directly in
print(f'My name is {name},My age is {age}')
#{} Run expression
print(f'{1+2+3}')
# Call Python built-in functions
print(f'{name.upper()}')
# Use lambda anonymous functions: you can do complex numerical calculations
fun = lambda x : x+1print(f'{fun(age)}')
# Output
My name is xiaoming,My age is 126
XIAOMING
13
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