# for loop - range (one argument)

## Objective

After working through this lesson, you’ll be able to

* Write Python code using the for loop using the range function with one argument.

{% embed url="<https://docs.google.com/presentation/d/1AveaRWfw_gFcn-pLx33Wiw9HOFfon5pJtx-cGOwJGPk/edit?usp=sharing>" %}

## Introductory Problem

You worked on while loop menu code previously.  Run the code below and make sure you understand how it works.&#x20;

{% code title="menu.py" %}

```python
done = False
while not done:
    print("Menu")
    print("S - Start")
    print("Q - Quit")
    choice = input("Choice: ")
    if choice == "S":
        print("Start")
    elif choice == "Q":
        print("Exiting Menu!")
        done = True
```

{% endcode %}

{% hint style="info" %}
done is a Boolean variable and True is the sentinel value.
{% endhint %}

Add code for the Intro menu item when the user selects I. &#x20;

Using a while loop, print your name 5 times. &#x20;

{% code title="intro.py" %}

```python
done = False
while not done:
    print("Menu")
    print("I - Intro")
    print("Q - Quit")
    choice = input("Choice: ")
    if choice == "I":
        print("Introductory Problem")
        x = 0
        name = input("What's your name? ")
        while x < 5:
            print(name)
    elif choice == "Q":
        print("Exiting Menu!")
        done = True
```

{% endcode %}

## for loop

Previously, you used while loops to iterate over a range of integer values.  Now you will use a for loop with the range function with one argument.

![](/files/-Ld1TFkOIEArjlGIZDcn)

{% hint style="info" %}
Programmers us&#x65;**`x`**&#x6F;&#x72;**`i`**&#x61;s a stepper variable.
{% endhint %}

![](/files/-Ltvzdp9BHZsEci0pMfn)

## Examples

### Example 1

Add a Menu Item E1 - Example 1

Using a for loop, print your name 5 times.

{% code title="example1.py" %}

```python
done = False
while not done:
    print("Menu")
    print("I - Intro")
    print("Q - Quit")
    choice = input("Choice: ")
    if choice == "I":
        print("Introductory Problem")
        x = 0
        name = input("What's your name? ")
        while x < 5:
            print(name)
    elif choice == "Q":
        print("Exiting Menu!")
        done = True
    elif choice == "E1":
        print("Example 1")
        name = input("What is your name? ")
        for i in range(5):
            print(name)
```

{% endcode %}

### Example 2

Add a Menu Item E2 - Example 2

Using a for loop, print numbers from 0 to 4.

{% code title="example2.py" %}

```python
done = False
while not done:
    print("Menu")
    print("S - Start")
    print("E2 - Example 2")
    print("Q - Quit")
    choice = input("Choice: ")
    if choice == "S":
        print("Starting Game!")
    elif choice == "Q":
        print("Exiting Menu!")
        done = True
    elif choice == "E2":
        print("Example 2")
        for i in range(5):
            print(i)
```

{% endcode %}

### Example 3

Add a Menu Item E3 - Example 3

Using a for loop, ask the user for 3 numbers.  Print the sum of numbers.

Initialize the variable sum to 0.

{% code title="example3.py" %}

```python
done = False
while not done:
    print("Menu")
    print("S - Start")
    print("E3 - Example 3")
    print("Q - Quit")
    choice = input("Choice: ")
    if choice == "S":
        print("Starting Game!")
    elif choice == "Q":
        print("Exiting Menu!")
        done = True
    elif choice == "E3":
        print("Example 3")
        sum = 0
        for i in range(3):
            num = int(input("Number: "))
            sum = sum + num
        print(sum)
```

{% endcode %}

### Example 4

Add a Menu Item E4 - Example 4

Using a for loop, create the table to show the numbers 0 to 10 and their squares.  Create a header:

print("Number\tSquared")

{% code title="example4.py" %}

```python
done = False
while not done:
    print("Menu")
    print("S - Start")
    print("E4 - Example 4")
    print("Q - Quit")
    choice = input("Choice: ")
    if choice == "S":
        print("Starting Game!")
    elif choice == "Q":
        print("Exiting Menu!")
        done = True
    elif choice == "E4":
        print("Number\tSquared")
        for i in range(11):
            print(i,"\t",i**2)
```

{% endcode %}

## Conclusion

* In your own words, what is a for loop?
* What are the differences between a while loop and a for loop.


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