Python String format()用法及代码示例

# Python3 program to demonstrate
# the str.format() method
  
# using format option in a simple string
print ("{}, A computer science portal for geeks."
                        .format("GeeksforGeeks"))
  
# using format option for a
# value stored in a variable
str = "This article is written in {}"
print (str.format("Python"))
  
# formatting a string using a numeric constant
print ("Hello, I am {} years old !".format(18)) 

# Python program demonstrating Index error
  
# Number of placeholders are four but
# there are only three values passed
  
# parameters in format function.
my_string = "{}, is a {} {} science portal for {}"
  
print (my_string.format("GeeksforGeeks", "computer", "geeks"))

# Python program using multiple place 
# holders to demonstrate str.format() method 
  
# Multiple placeholders in format() function
my_string = "{}, is a {} science portal for {}"
print (my_string.format("GeeksforGeeks", "computer", "geeks"))
  
# different datatypes can be used in formatting
print ("Hi ! My name is {} and I am {} years old"
                            .format("User", 19))
  
# The values passed as parameters
# are replaced in order of their entry
print ("This is {} {} {} {}"
       .format("one", "two", "three", "four"))

# To demonstrate the use of formatters
# with positional key arguments.
  
# Positional arguments
# are placed in order
print("{0} love {1}!!".format("GeeksforGeeks",
                                    "Geeks"))
  
# Reverse the index numbers with the
# parameters of the placeholders
print("{1} love {0}!!".format("GeeksforGeeks",
                                    "Geeks"))
  
  
print("Every {} should know the use of {} {} programming and {}"
    .format("programmer", "Open", "Source", "Operating Systems"))
  
  
# Use the index numbers of the
# values to change the order that
# they appear in the string
print("Every {3} should know the use of {2} {1} programming and {0}"
        .format("programmer", "Open", "Source", "Operating Systems"))
  
  
# Keyword arguments are called
# by their keyword name
print("{gfg} is a {0} science portal for {1}"
.format("computer", "geeks", gfg ="GeeksforGeeks"))

# Demonstrate ValueError while
# doing forced type-conversions
  
# When explicitly converted floating-point
# values to decimal with base-10 by 'd' 
# type conversion we encounter Value-Error.
print("The temperature today is {0:d} degrees outside !"
                                        .format(35.567))
  
# Instead write this to avoid value-errors
''' print("The temperature today is {0:.0f} degrees outside !"
                                            .format(35.567))'''

# Convert base-10 decimal integers 
# to floating point numeric constants
print ("This site is {0:f}% securely {1}!!".
                    format(100, "encrypted"))
  
# To limit the precision
print ("My average of this {0} was {1:.2f}%"
            .format("semester", 78.234876))
  
# For no decimal places
print ("My average of this {0} was {1:.0f}%"
            .format("semester", 78.234876))
  
# Convert an integer to its binary or
# with other different converted bases.
print("The {0} of 100 is {1:b}"
        .format("binary", 100))
          
print("The {0} of 100 is {1:o}"
        .format("octal", 100))

# To demonstrate spacing when 
# strings are passed as parameters
print("{0:4}, is the computer science portal for {1:8}!"
                        .format("GeeksforGeeks", "geeks"))
  
# To demonstrate spacing when numeric
# constants are passed as parameters.
print("It is {0:5} degrees outside !"
                        .format(40))
  
# To demonstrate both string and numeric
# constants passed as parameters
print("{0:4} was founded in {1:16}!"
    .format("GeeksforGeeks", 2009))
  
  
# To demonstrate aligning of spaces
print("{0:^16} was founded in {1:<4}!"
        .format("GeeksforGeeks", 2009))
  
print("{:*^20s}".format("Geeks"))

# which prints out i, i ^ 2, i ^ 3,
#  i ^ 4 in the given range
  
# Function prints out values
# in an unorganized manner
def unorganized(a, b):
    for i in range (a, b):
        print ( i, i**2, i**3, i**4 )
  
# Function prints the organized set of values
def organized(a, b):
    for i in range (a, b):
  
        # Using formatters to give 6 
        # spaces to each set of values
        print("{:6d} {:6d} {:6d} {:6d}"
        .format(i, i ** 2, i ** 3, i ** 4))
  
# Driver Code
n1 = int(input("Enter lower range:-\n"))
n2 = int(input("Enter upper range:-\n"))
  
print("------Before Using Formatters-------")
  
# Calling function without formatters
unorganized(n1, n2)
  
print()
print("-------After Using Formatters---------")
print()
  
# Calling function that contains
# formatters to organize the data
organized(n1, n2)

introduction = 'My name is {first_name} {middle_name} {last_name} AKA the {aka}.'
full_name = {
    'first_name':'Tony',
    'middle_name':'Howard',
      'last_name':'Stark',
      'aka':'Iron Man',
}
  
# Notice the use of "**" operator to unpack the values.
print(introduction.format(**full_name))