Week-7-1

Introduction to Strings

• Strings: Sequence of characters identified by specific index starting from zero.

String Slicing

• Definition: Substring extraction using slice notation string[start:end] with start inclusive and end exclusive.

• Examples:

  • my_string[0:2] -> "He"

  • my_string[7:10] -> "Wor"

• New String Objects: Slicing creates new strings (e.g., animal = my_string[4:7]).

Using Slice Notation

• Missing End Index: my_string[8:] extracts till the end.

• Negative Indices: Count from the end of the string (e.g., my_string[-5]).

Understanding Stride

• Definition: string[start:end:stride] allows index increments (e.g., my_string[0:9:2]).

String Methods

• Replace: string.replace(old, new, count) for substring replacement.

• Find Methods: find(substring) locates first occurrence; count(substring) counts occurrences.

• Membership: Use in to check for substring presence.

String Comparisons

• Lexicographical Order: Based on ASCII values (e.g., "y" > "a").

String Character Checks and Formatting

• Methods: isalpha(), isdigit(), islower(), isupper(), isspace() for various checks.

• Formatting: strip() for whitespace, capitalize() for first letter, and title() to capitalize each word.