op_string.py

fruit = "banana"
# length of a string
l = len(fruit)
# iterating through a string
for letter in fruit:
  print(letter)
# checking if a string or a substring exists in another
print("anana" in fruit)
# comaparing maj and min
fruit_upper = 'BANANA'
fruit_lower = 'banana'
print(fruit_upper > fruit_lower)   # False because uppercases are lower than lowercases

# lower and upper methods
fruit_lower = fruit.lower()  # lower all uppercases
fruit_upper = fruit.upper()  # upper all lowercases 

# find function returns the position of the string or the substring
print(fruit.find('na')) 
>>2

# replace function replace a substring by another one. All occurences of that substring are replaced.
greet = 'Hello Bob'
nstr = greet.repalce('Bob', 'Jane')