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# Python type conversion examples

# 1. Converting a string to an integer
age = int("25")
print("1:", "String '25' converted to integer:", age)

# 2. Converting a string to a float
price = float("19.99")
print("2:", "String '19.99' converted to float:", price)

# 3. Converting an integer to a string
result_str = "Your score is " + str(90) + " points."
print("3:", result_str)

# 4. Example where an error occurs
# try-except is used to handle errors that occur in the try block
# and process them in the except block
try:
    number = int("abc")
except ValueError:
    print("4:", "'abc' cannot be converted to an integer.")

# Converting Between Strings and Numbers

In programming, you often need to convert between `numbers` and `strings`.

For example, you might need to display the result of a calculation or convert user-entered text to a number for further calculations.

This process of converting one data type to another is known as **Type Conversion**.

 

## Why Do We Need to Convert Data Types?

In programming, all data has a **data type**.

For example, the number `3` and the string `"3"` are fundamentally different.

You can't directly calculate or compare different data types, so sometimes you need to match the data types for accurate operations.

 

### Converting Strings to Numbers with int() and float()

Sometimes, you need to convert a string that represents a number, like `"5"`, to an actual numeric type like `5`.

For example, if you try to add `"5" + 3`, it will cause an error.

In Python, you can handle such cases by using `int()` and `float()` functions to convert strings to numbers.

```python title="Converting strings to numbers"
age_str = "25"

# Convert string to integer
age = int(age_str)

# Prints 30
print(age + 5)

price_str = "19.99"

# Convert string to float
price = float(price_str)

# Prints 9.99
print(price - 10)
```

As shown above, `int()` converts a string to an integer, and `float()` converts a string to a floating-point number.

 

### Converting Numbers to Strings with str()

Conversely, you might sometimes want to display a number together with a string.

```python title="Converting numbers to strings"
score = 90

# "Your score is " is a string but score is a number, causing an error
result_str = "Your score is " + score
# TypeError: can only concatenate str (not "int") to str
```

 

To convert a number to a string, you use the `str()` function.

```python title="Converting numbers to strings"
score = 90

# Convert the number to a string and concatenate
result_str = "Your score is " + str(score)

# Prints: Your score is 90
print(result_str)
```

The `str()` function converts numbers to strings, allowing them to be easily combined with other strings.

 

## What Should You Be Careful About When Converting?

When converting data types, always ensure that the value you're converting can actually be converted.

For example, trying to convert a string like `"abc"` to an integer with the `int()` function will cause an error.

```python title="Incorrect conversion example"
text = "abc"

# Error: ValueError
number = int(text)
```

The `int()` function is used to convert a string to an integer. For example, converting the string '25' with `int('25')` results in the integer 25.

The `int()` function in Python converts a string to an integer.