Reading questions

Question

Readings: Python_by_Lambert

Chapter 4, Section 4.1 Substrings 

1. Assume that the variable data refers to the string “myprogram.exe”

     Write the values of the following expressions:

1. data[2]
2. data[-1]
3. len(data)
4. data[0:8]
5. “gram” in data and “pro” in data
6. Assume that the variable data refers to the string “myprogram.exe”.

     Write the expressions that perform the following tasks:

1. Extract the substring “gram” from data.
2. Truncate the extension “.exe” from data.
3. Extract the character at the middle position from data.
4. Assume that the variable myString refers to a string. Write a code segment

      that uses a loop to print the characters of the string in reverse order.

1. Assume that the variable myString refers to a string and the variable

      reversedString refers to an empty string. Write a loop that adds the

     characters from myString to reversedString in reverse order.

Answer 1

(1)

i. data[2] = 'p'; the third character in the string 'myprogram.exe'. indexing starts at 0 so the third character is the second index.

ii. data[-1] = 'e'; the last character in the string 'myprogram.exe'. negative indicates indexed from the end.

len(data) = 13; the length of the string 'myprogram.exe'

iv. data[0:8] = 'myprogra'; the firsts through the eighth character (at the seventh index) in the string 'myprogram.exe'

v. 'gram' in data and 'pro' in data = true. if the string 'myprogram.exe' contains the substring 'gram' and the substring 'pro'.

(2)

i. data[5:9]

ii. data[0:-4]

iii. data[6]

(3)

for i in range(1, len(myString)):

print(myString[-i])

(4)

for i in range(1, len(myString)):

reversedString = reversedString + data[-i]