Add changes to Strings lesson

Author: kochaika

Strings/Basic string methods/task.md

@@ -6,7 +6,9 @@ uppercase. To call any string method, type a dot after the string (or a variable
 the string) and the method name after it, e.g., `"John".upper()`. In PyCharm, you can 
 explore all available string methods by using the &shortcut:CodeCompletion; shortcut after the dot. 
 Detailed information about all string methods can be found <a href="https://docs.python.org/3/library/stdtypes.html#string-methods">here</a>.
-  
+
+For more structured and detailed information, you can refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/6842).
+
 Print `monty_python` in upper case using an appropriate string method.  
 
 <div class='hint'>Pay attention to how the <code>lower()</code> method is used in our code.</div>

Strings/Character escaping/character_escaping.py

@@ -1,4 +1,6 @@
-dont_worry = "Don't worry about apostrophes"
-# print(dont_worry)
-# print("\"Sweet\" is an ice-cream")
+dont_worry = "Don't worry about single quote if the string is in double quotes and vice versa"
+print(dont_worry)
+
+print("\"Sweet\" is an ice-cream")
+
 print('The name of this ice cream is "Sweet\'n\'Tasty"')

Strings/Character escaping/task-info.yaml

@@ -1,13 +1,13 @@
 type: edu
 files:
-- name: character_escaping.py
-  visible: true
-  placeholders:
-  - offset: 109
-    length: 47
-    placeholder_text: ???
-- name: tests/__init__.py
-  visible: false
-- name: tests/test_task.py
-  visible: false
-feedback_link: https://docs.google.com/forms/d/e/1FAIpQLSfRlDlldKfuq-cHMNFfHMER61P1PRIan7KG6yp1GvaweDI7GA/viewform?usp=pp_url&entry.2103429047=Strings+/+Character+Escaping
+  - name: character_escaping.py
+    visible: true
+    placeholders:
+      - offset: 157
+        length: 47
+        placeholder_text: ???
+  - name: tests/__init__.py
+    visible: false
+  - name: tests/test_task.py
+    visible: false
+feedback_link: https://docs.google.com/forms/d/e/1FAIpQLSfRlDlldKfuq-cHMNFfHMER61P1PRIan7KG6yp1GvaweDI7GA/viewform?usp=pp_url&entry.2103429047=Strings+/+Character+Escaping

Strings/Character escaping/task.md

@@ -16,12 +16,13 @@ If you need to print quotes inside a string, use a different kind of quotes: sin
 marks may be used in a double-quoted string without escaping, and vice versa. Also, as a side note, it is a good 
 idea to pick your favorite kind of quotes and use them consistently.
 
-You can learn more about escaping from <a href="https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals">this section</a> of Python Documentation.  
+You can learn more about escaping from <a href="https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals">this section</a> of Python Documentation.
+
+For more structured and detailed information, you can also refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/7130).
 
 Print out the following text using one string:  
 ```text
 The name of this ice cream is "Sweet'n'Tasty"  
 ```
 
-
 <div class='hint'>Use the backslash to escape quotes.</div>

Strings/Character escaping/tests/test_task.py

@@ -8,7 +8,7 @@ def test_string(self):
         f = io.StringIO()
         with contextlib.redirect_stdout(f):
             import character_escaping
-        output = f.getvalue()[:-1]
+        output = f.getvalue().split('\n')[-2]
         string = 'The name of this ice cream is "Sweet\'n\'Tasty"'
         self.assertEqual(string, output, msg='Wrong result string.')
 

Strings/F-strings/task.md

@@ -29,6 +29,8 @@ f"{name.lower()} is funny."
 ```
 For more information about formatted string literals you can refer to <a href="https://docs.python.org/3/reference/lexical_analysis.html#formatted-string-literals">Python Docs</a>.
 
+For more structured and detailed information, you can also refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/6037).
+
 Try creating an f-string yourself. Also try running the code to see what it prints.
 
 <div class="hint">The value assigned to the <code>name</code> variable has to be a string, so it needs to be in quotes, 

Strings/String formatting/task.md

@@ -12,7 +12,9 @@ or decimal values.
 > interface, or <a href="https://docs.python.org/3/library/string.html#template-strings">template strings</a> may help avoid these errors. 
 > Each of these alternatives provides their own trade-offs and benefits of 
 > simplicity, flexibility, and/or extensibility.</i>
-  
+
+For more structured and detailed information, you can refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/6037).
+
 Tell PyCharm how old you are (using digits).  
 
 <div class='hint'>Use the <code>%d</code> special symbol.</div>

Strings/String indexing/task.md

@@ -8,7 +8,9 @@ when `x` is not found in the string.
 Indices may also be negative numbers if you need to start counting from the right 
 (i.e., from the end of your string). 
 Note that since `-0` is the same as `0` , negative indices start from `-1`.  
-  
+
+For more structured and detailed information, you can refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/6189).
+
 Use the index operator to get the letter `"P"` from `"Python"` .  
 
 <div class="hint">Note that indices start with 0.</div>

Strings/String length/task-info.yaml

@@ -5,10 +5,10 @@ files:
   placeholders:
   - offset: 200
     length: 23
-    placeholder_text: '"???"'
+    placeholder_text: ???
   - offset: 121
     length: 20
-    placeholder_text: '"???"'
+    placeholder_text: ???
 - name: tests/__init__.py
   visible: false
 - name: tests/test_task.py

Strings/String length/task.md

@@ -1,7 +1,22 @@
 ## String length
 
-The `len()` method is used to count how many characters a string contains.  
-  
+The `len()` method is used to count how many characters a string contains.
+
+For example:
+```python
+s = "Hello World"
+print(len(s))   # will print 11
+```
+
+Note, that result of `/` division have type float:
+```python
+a = 10/2
+print(a)        # 5.0
+print(type(a))  # <class 'float'>
+```
+
+For more structured and detailed information, you can refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/5814).
+
 Get the first half of the string stored in the variable `phrase`.  
 Note: when getting the index, remember about type conversion.  
 

Strings/String length/tests/test_task.py

@@ -18,3 +18,8 @@ def test_index(self):
     class TestCase(unittest.TestCase):
         def test_fail(self):
             self.assertTrue(False, msg="Do not rename any variables.")
+
+except TypeError:
+    class TestCase(unittest.TestCase):
+        def test_fail(self):
+            self.assertTrue(False, msg="Don't forget to convert the result of division to int type")

Strings/String negative indexing/task.md

@@ -2,7 +2,9 @@
 
 As we said, you can use negative indices to count characters ‘backwards’ starting
 from the end of a string.  
-  
+
+For more structured and detailed information, you can refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/6189).
+
 Use a negative index to get the `'!'` sign from `long_string`.   
 
 <div class='hint'>Use a negative index.</div>

Strings/String slicing/task.md

@@ -24,6 +24,8 @@ str[:end]      # items from the beginning through end-1
 str[:]         # a copy of the whole array
 </code></pre>
 
+For more structured and detailed information, you can refer to [this Hyperskill knowledge base page](https://hyperskill.org/learn/step/6177).
+
 Use slicing to get `"Python"` from the `monty_python` variable.  
 
 <div class='hint'>You can leave one of the indices empty.</div>