--- title: 3.14 Numeric Type Conversion description: "Numeric type conversion is the process of converting a value from one numeric data type to another. Python provides built-in functions for converting between numeric types. The three most commonly used conversion functions are: - `int()` – Converts a value…" url: "https://edcret.in/docs/python-programming/numeric-data-types-python/3-14-numeric-type-conversion/" updated: "2026-07-29" category: Python Programming / Numeric Data Types --- # 3.14 Numeric Type Conversion Numeric type conversion is the process of converting a value from one numeric data type to another. Python provides built-in functions for converting between numeric types. The three most commonly used conversion functions are: - `int()` – Converts a value to an integer. - `float()` – Converts a value to a floating-point number. - `complex()` – Converts a value to a complex number. Type conversion is useful when working with user input, performing calculations, or ensuring that values have the correct data type. --- ## Syntax ``` int(value) float(value) complex(value) ``` ### Conversion Functions | Function | Description | | --- | --- | | `int()` | Converts a value to an integer. | | `float()` | Converts a value to a floating-point number. | | `complex()` | Converts a value to a complex number. | --- ## Example 1: Convert Integer to Float **main.py** ``` number = 25 result = float(number) print(result) print(type(result)) ``` ### Output ``` 25.0 ``` ### Explanation - `number` stores an integer. - `float()` converts it into a floating-point number. - The value becomes `25.0`. --- ## Example 2: Convert Float to Integer **main.py** ``` number = 15.98 result = int(number) print(result) print(type(result)) ``` ### Output ``` 15 ``` ### Explanation - `int()` removes the fractional part. - It does **not** round the number. - Therefore, `15.98` becomes `15`. --- ## Example 3: Convert Integer to Complex **main.py** ``` number = 12 result = complex(number) print(result) print(type(result)) ``` ### Output ``` (12+0j) ``` ### Explanation - `complex()` converts the integer into a complex number. - The imaginary part is automatically set to `0j`. --- ## Example 4: Convert Float to Complex **main.py** ``` number = 8.5 result = complex(number) print(result) ``` ### Output ``` (8.5+0j) ``` ### Explanation - A floating-point value can also be converted into a complex number. - The imaginary part is `0j`. --- ## Example 5: Convert String to Integer **main.py** ``` number = "250" result = int(number) print(result) print(type(result)) ``` ### Output ``` 250 ``` ### Explanation - The original value is a string. - `int()` converts the numeric string into an integer. - The data type changes from `str` to `int`. --- ## Example 6: Convert String to Float **main.py** ``` number = "45.75" result = float(number) print(result) print(type(result)) ``` ### Output ``` 45.75 ``` ### Explanation - `float()` converts the numeric string into a floating-point number. - The decimal value is preserved. --- ## Example 7: User Input Conversion **main.py** ``` age = int(input("Enter your age: ")) print(age) print(type(age)) ``` ### Sample Input ``` 21 ``` ### Output ``` 21 ``` ### Explanation - `input()` always returns a string. - `int()` converts the input into an integer. - The converted value can be used in calculations. --- ## Example 8: Arithmetic After Conversion **main.py** ``` price = "100" total = int(price) + 50 print(total) ``` ### Output ``` 150 ``` ### Explanation - The string `"100"` cannot be added directly to an integer. - `int()` converts it into a numeric value. - Arithmetic can then be performed normally. --- ## Example 9: Convert Boolean Values **main.py** ``` print(int(True)) print(float(False)) ``` ### Output ``` 1 0.0 ``` ### Explanation - `True` is converted to `1`. - `False` is converted to `0`. - Boolean values behave like integers during numeric conversion. --- ## Example 10: Checking Multiple Conversions **main.py** ``` print(type(int(5.5))) print(type(float(5))) print(type(complex(5))) ``` ### Output ``` ``` ### Explanation - `int(5.5)` returns an integer. - `float(5)` returns a floating-point number. - `complex(5)` returns a complex number. - Each conversion changes the data type appropriately. --- # Common Mistakes ### 1. Expecting `int()` to Round Numbers **Incorrect** ``` print(int(8.9)) ``` ### Incorrect Expectation ``` 9 ``` ### Actual Output ``` 8 ``` **Reason** `int()` removes the fractional part instead of rounding the value. **Correct** ``` print(round(8.9)) ``` --- ### 2. Converting a Non-Numeric String **Incorrect** ``` print(int("hello")) ``` ### Output ``` ValueError: invalid literal for int() with base 10: 'hello' ``` **Reason** Only strings representing valid numbers can be converted to numeric types. --- ### 3. Passing a Complex Number to `int()` **Incorrect** ``` print(int(3 + 4j)) ``` ### Output ``` TypeError: can't convert complex to int ``` **Reason** Complex numbers cannot be converted directly to integers. --- ### 4. Expecting Conversion Functions to Modify the Original Variable **Incorrect** ``` number = "25" int(number) print(type(number)) ``` ### Output ``` ``` **Reason** Conversion functions return a new value. They do not modify the original variable. **Correct** ``` number = int(number) print(type(number)) ``` --- # Best Practices - Convert values to the required data type before performing calculations. - Always validate user input before converting it. - Remember that `int()` truncates the fractional part instead of rounding. - Store the converted value if it will be used later. - Use the conversion function that matches the required numeric type. --- # Key Points to Remember - Python provides `int()`, `float()`, and `complex()` for numeric type conversion. - `int()` converts values to integers by removing the fractional part. - `float()` converts values to floating-point numbers. - `complex()` converts values to complex numbers. - Numeric strings can be converted if they contain valid numeric data. - Conversion functions return new values and do not modify the original variables. - Invalid conversions raise exceptions such as `ValueError` or `TypeError`.