feat(example): strings

Author: ashegde

codes/session_1/string.py

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+# Open terminal > python3
+# Start typing below commands and see the output
+
+# Use single quote
+'Ashwin'
+
+'Ashwin\'s'
+
+# Use double quote
+"Ashwin's"
+
+"Hello \"Ashwin\" "
+
+name = 'Ashwin Hegde\nashwin.hegde3@gmail.com'
+name # Without print() => \n has no effect
+print(name) ## \n means new line
+
+print('C:\python\name')
+print(r'C:\python\name') # r before single quote
+
+# String in multi line, 1 way using triple-quotes """...""" or '''...'''
+print("""\
+  Usage: python-cli [options]
+      -h help
+      -H hostname
+""")
+
+# String can be concate using +
+'Ashwin' + 'Hegde'
+
+# 2 or more string only (no variable or no expression) kept next to each other are automatically concate
+'Ash' 'win' ' ' 'Hegde'
+
+# String can be repeat using *
+'Ashwin will' + 3 * ' Win'
+
+# Handling long strings
+text = ('Hello World! My name is Ashwin '
+        'and we are learning Python Syntax!')
+text
+
+# String index (starts from left)
+# and negative index (starts from right and from -1)
+name = 'Ashwin'
+name[0] # A
+name[5] # n
+name[7] # IndexError: String index out of range
+name[-1] # n
+name[-3] # w
+
+# Slicing
+name[3:6] # win => 3 included, 6 excluded
+name[3:] # win
+name[:3] # Ash
+
+# How Slice works?
+#  +---+---+---+---+---+---+
+#  | P | y | t | h | o | n |
+#  +---+---+---+---+---+---+
+#  0   1   2   3   4   5   6
+# -6  -5  -4  -3  -2  -1
+
+# String length
+len('Ashwin') # 6
+