''' Purpose: continue string manipulation introduction
'''

print()

# Operator [] is the string index operator -- it provides access to
# a string subsequence. Depending upon its operands it is all called
# subscripting and slicing. Here we only care about subscripting.
# The subscript is an index value. In Python index values start at 0.

print( '### [] is the string index operator' )
s = 'change'

n = len( s ) # len( s ) gives you the length of the string (number of characters in the string)

print( 's =', s, )
print( '    0123456' )

print()

print( 'n = len( s ) =', n )

print()

print( '### If the [] operand is an integer value, it is subscripting' )
x = s[ 0.0 ] # Can't do this!
y = s[ 4 ] # Can't subscript if the index doesn't exist in the string (ex. when you have length 3 and try to get index 4)
z = s[ n-1 ]

# WRITE THIS DOWN:
    # For a string, the first character is always at index 0 and the last character is at
    # len( string ) - 1

# 'CS1112'
#  012345
# Length 6
# First character 'C' at index 0
# Last character '2' at index 5 (which is 6 - 1 = len('CS1112')-1)
# Subscripting - Getting a character at an index in a string
# Indexes are number positions for characters in a string! They're the number positions
# where the characters are!

print( 's[ 0 ] = ', x )
print( 's[ 4 ] = ', y )
print( 's[ n-1 ] = ', z )