how to check if string only contains letters python code example

Example 1: python if string contains char

myString = "<text contains this>"
myOtherString = "AnotherString"

# Casting to string is not needed but it's good practice
# to check for errors 

if str(myString) in str(myOtherString): 
    # Do Something
else:
	# myOtherString didn't contain myString

Example 2: python check if string contains substring

string = "My favourite programming language is Python"
substring = "Python"

if substring in string:
    print("Python is my favorite language")
elif substring not in string:
    print("Python is not my favourite language")