Unit 4 - Lesson 1

34.1.1. Introduction to Strings

str= input("str: ")
print(str)

34.2.1. Operations of Strings

# Prompt the user to enter a string
s = input("String: ")
# Print entire string
print(s) 

# Print second character of string from beginning
print("Second character from first:",s[1])

# Print second character of string from end 
print("Second character from end:",s[-2])

34.2.2. Understanding Slicing Operator

(a)The last character of the string, including it.

34.2.3. Different examples on Slicing Operations

(b)"DEFGH"

34.2.4. Write a program to print a string after removing first and last characters

str = input("str: ")
print("output:", str[1:-1])

34.2.5. Concatenation of strings

str1 = input("str1: ")
str2 = input("str2: ")
print(str1, str2)

34.2.6. Program to perform concatenation on two strings.

str1 = input("str1: ")
str2= input("str2: ")
print("result: "+str1+str2+str2+str1)

34.2.7. Program to remove a character from string based on integer value given by the user.

str = input("str: ")
num = int(input("num: "))
if(len(str)>num):
	print("output:",str[0:num]+str[(num+1):])
else:
	print("num should be positive, less than the length of str")

34.2.8. Program to print the concatenated string by excluding first character.

str1 = input("str1: ")
str2 = input("str2: ")
if len(str1)<=1:
	print("null")
else:
	print("output:",str1[1:]+str2[1:])

34.2.9. Program to swap first and last characters of given string and display the result.

str = input("str: ")
if len(str) == 0:
	print("null")
elif len(str) == 1:
	print(str)
else:
	print("output:",str[-1]+str[1:-1]+str[0])

34.2.10. Program to print first and last two characters of given string

#Type Content here...
i = input("input: ")
if(len(i)>3):
	print("output:",i[0:2]+i[-2:])
else:
	print("output:",i)

34.2.11. Understanding Membership Operator

(c)print('z' not in str) returns True

34.2.12. Repetitions of a String

a = input("str: ")
print(a*4)
print(a[::-1]*3)

34.2.13. Program to print 3 copies of first three characters of a string.

a = input("str: ")
if len(a)<3:
	print("result:",a)
else:
	print("result:",a[0:3]*3)

34.2.14. Program to print a given string which repeats 'n' times.

a = input("str: ")
b = int(input("num: "))
print("result: "+a*b)

34.2.15. Program to repeat first n characters of the given string n times

a = input("str: ")
b = int(input("num: "))
if b>0:
	print("result:", a[0:b]*b)
else:
	print("num should be positive, less than length of str")

34.2.16. Understanding String Immutability

(a)Deleting characters within strings violates the immutability principle of strings.