python learning the next day - and a string formatted output

# String 
# String Value: String name [index] can only take a single value 
# n access sequence, starting from 0 
str1 = "Hello World" 
Print (str1 [. 3]) # Output "l" 

Reverse Order Access # , starting from -1 
print (str1 [-3]) # output "R & lt" 

# string operations: +, * 
str2 = "!!! Go Go Go" 
Print (str1 + str2) # output "hello world go go! ! Go! " 
Print (str2 * 2) output #" Go! Go! Go! Go! Go! Go! " 

# Analyzing string in, not in member operator 
print ( '0' in str1) # output" False " 
print ( '0' not in str1 ) # output "True" 

# different types of stitching 
NUM = 9527 
#Print (str2 + NUM) # given 
print (str2 + str (num) ) # output "go! go! go! 9527 " str function converts a type 

# string sections 
# string name [m: n: k] m : where index of the n: index of the end where +1 k: step 
print (str1 [3: 7] ) # output "lo w "k default. 1 
Print (str1 [. 3: 10: 2]) # outputs" L OL " 
Print (str1 [:]) # Output "hello world"


# Formatted output 
# first:% d integers% f float% s string 
name = "Wang Jin when" 
Age = 20 
the Math = 84.25 
Print ( "% s% d years old this year, mathematics exam% .3f points"% (name, age, math)) # output "when 20-year-old Wang Jin, 84.250 points in math" 
#% d can only put an integer;% f can put an integer, you can also put a float;% s may be a laissez-faire a value 
# second: format {} 
Print ( "{} {} years old this year, the math sub {}" .format (name, age, math )) # output "Wang Jin 20 years old this year, 84.25 math exam points " 
Print (" {1} {0} years old this year, the math {2} points ".format (age, name, math )) # output" Wang Jin 20 years old this year, up 84.25 points in math. "