Merge pull request #372 from realpython/python-input-integer-materials

Source code for python-input-integer

Author: KateFinegan

python-input-integer/README.md

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+# How to Read Python Input as Integers
+
+Here you can find code examples for the tutorial [How to Read Python Input as Integers](https://realpython.com/python-input-integer/).
+
+The file [`number_input.py`](number_input.py) contains the `get_integer()` function discussed in the tutorial plus some other utility functions for numeric input.

python-input-integer/number_input.py

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+"""Utility functions for prompting users for numeric input.
+
+This file accompanies the Real Python tutorial How To Read User Input As
+Integers. It contains examples of functions that filter user input for valid
+integers and floats.
+"""
+
+
+def get_integer(prompt: str, error_message: str = None) -> int:
+    """Prompts the user for an integer value.
+
+    If the input is invalid, prints error_message (if specified) and then
+    repeats the prompt.
+    """
+    while True:
+        try:
+            return int(input(prompt))
+        except ValueError:
+            if error_message:
+                print(error_message)
+
+
+def get_float(prompt: str, error_message: str = None) -> float:
+    """Prompts the user for a float value.
+
+    If the input is invalid, prints error_message (if specified) and then
+    repeats the prompt.
+    """
+    while True:
+        try:
+            return float(input(prompt))
+        except ValueError:
+            if error_message:
+                print(error_message)
+
+
+def get_integer_with_default(
+    prompt: str, default_value: int, error_message: str = None
+) -> int:
+    """Prompts the user for an integer, and falls back to a default value.
+
+    If the input is an empty string, then the function returns default_value.
+    Otherwise, if the input is not a valid integer, prints error_message (if
+    specified) and then repeats the prompt.
+    """
+    while True:
+        input_string = input(prompt)
+        if not input_string:
+            return default_value
+        try:
+            return int(input_string)
+        except ValueError:
+            if error_message:
+                print(error_message)
+
+
+if __name__ == "__main__":
+    # Test functions when running as a script.
+    print(get_integer("Test get_integer(): "))
+    print(
+        get_integer(
+            "Test get_integer() with an error message: ",
+            error_message="Invalid integer!",
+        )
+    )
+    print(
+        get_float(
+            "Test get_float() with an error message: ",
+            error_message="Invalid float!",
+        )
+    )
+    print(
+        get_integer_with_default(
+            "Test get_integer_with_default(): ",
+            default_value=99,
+            error_message="That's not a valid integer!",
+        )
+    )