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Author: profcalculus

number_input_examples.py

@@ -0,0 +1,61 @@
+# number_input_examples.py
+
+# This file accompanies the Real Python article "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. If the input is an empty string,
+    # 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 input_string == "":
+            return default_value
+        try:
+            result = int(input_string)
+            return result
+        except ValueError:
+            if error_message:
+                print(error_message)
+
+
+# Run this file as a main module
+# (ie python number_input_examples.py)
+# to perform simple interactive testing of the functions.
+
+if __name__ == "__main__":
+    print(get_integer("Testing get_integer(): "))
+    print(
+        get_integer("Testing get_integer() with an error message: ", "Invalid integer!")
+    )
+    print(get_float("Testing get_float() with an error message: ", "Invalid float!"))
+    print(
+        get_integer_with_default(
+            "Testing get_integer_with_default(): ", 99, "That's not a valid integer!"
+        )
+    )