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AQA GCSE · Question 12.2 · Programming
Figure 12 shows a line of Python code that creates a list of fruit names.
Figure 12
python
fruits = ["banana", "apple", "orange", "pear", "grape", "pineapple"]
Extend the program in Figure 12. Your answer must be written in Python.
The program should get the user to enter a word and perform a linear search on the list fruits to find if the word is in the list or not.
The program should:
- ask the user what word they would like to find
- output the message
True if the word is found
- output the message
False if the word is not found.
You must write your own linear search routine and not use any built-in search function available in Python.
Figure 12 shows a line of Python code that creates a list of fruit names.
Figure 12
python
fruits = ["banana", "apple", "orange", "pear", "grape", "pineapple"]
Extend the program in Figure 12. Your answer must be written in Python.
The program should get the user to enter a word and perform a linear search on the list fruits to find if the word is in the list or not.
The program should:
- ask the user what word they would like to find
- output the message
Trueif the word is found - output the message
Falseif the word is not found.
You must write your own linear search routine and not use any built-in search function available in Python.
How to approach this question
1. **Get Input:** Use `input()` to get the word to search for from the user. Store it in a variable, e.g., `word_to_find`.
2. **Initialize a Flag:** Create a boolean variable, e.g., `found = False`. This variable will keep track of whether the word has been found. It starts as `False` because we haven't found it yet.
3. **Loop Through the List:** Use a `for` loop to iterate through each item in the `fruits` list. For example: `for fruit in fruits:`.
4. **Check for a Match:** Inside the loop, use an `if` statement to compare the current item (`fruit`) with the user's input (`word_to_find`).
5. **Update Flag and Exit:** If they match (`if fruit == word_to_find:`), set your flag to `True` (`found = True`) and use `break` to exit the loop, as there is no need to search further.
6. **Print Result:** After the loop has finished, print the final value of your `found` variable.
Full Answer
python
fruits = ["banana", "apple", "orange", "pear", "grape", "pineapple"]
# Ask the user for the word to find
word_to_find = input("Enter a fruit to search for: ")
# Perform a linear search
found = False
for fruit in fruits:
if fruit == word_to_find:
found = True
break # Stop searching once found
# Output the result
print(found)
A linear search is the simplest search algorithm. It sequentially checks each element of the list until a match is found or the whole list has been searched.
The Python solution implements this as follows:
1. `word_to_find = input(...)`: Gets the target word from the user.
2. `found = False`: A "flag" variable is created. Its value will be changed to `True` only if we find a match.
3. `for fruit in fruits:`: This loop iterates through every element in the `fruits` list, assigning the current element to the variable `fruit` in each pass.
4. `if fruit == word_to_find:`: Inside the loop, this checks if the current fruit is the one we are looking for.
5. `found = True`: If a match is found, we "raise the flag" by setting `found` to `True`.
6. `break`: This is an important optimization. Once the item is found, there's no need to check the rest of the list, so `break` immediately exits the loop.
7. `print(found)`: After the loop finishes (either by `break` or by checking all items), this line prints the final state of the `found` flag, which will be `True` if a match was made, and will remain `False` otherwise.
Common mistakes
✗ Using the built-in Python `in` operator (e.g., `if word_to_find in fruits:`), as the question explicitly forbids this.\n✗ Forgetting to initialize the `found` flag before the loop.\n✗ Printing inside the loop, which could result in multiple outputs.
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