Python contains many built-in methods that make it a convenient and accessible language. The **`eval()` method** is one such method. It parses and evaluates an *expression* as an argument.

#    
## Syntax

The following is the function prototype:

```python
eval(expression, globals, locals)
```

The syntax shown above represents the Python `eval()` method and the argument it parses. 

#   
## Parameters  
It takes three parameters which are described below.

- **`expression`**: It evaluates a `String` parsed as a Python expression and returns its result as an `Integer`.

- **`globals`**: It represents a Python dictionary that specifies the available global variables and methods. It is an optional parameter.

- **`locals`**: It is similar to the `globals` parameter described above but it specifies the available local methods and variables. It is also an optional parameter.

## Evaluating an expression

The Python `eval()` method evaluates a string-based expression by carrying out the following:
1. Parsing an expression.
2. Compilation to bytecode.
3. Evaluation as a Python expression.
4. Returning the evaluated expression as a result.

Below is an example that uses the `eval()` method. It takes in a string and converts it into an integer, float, or complex number.

## Code

number = "50"
print(eval(number), type(eval(number)))

float_number = "50.33"
print(eval(float_number), type(eval(float_number)))

complex_number = "1+2j"
print(eval(complex_number), type(eval(complex_number)))

## Output
>`50`
>
> `50.33`
>
>`(1+2j)`

The `eval()` function in the example above was able to identify the expressions in the string and convert them to their respective types. Note that if characters and alphabets are parsed as an expression, it would return an error. Another example is shown below.

# Solving mathematical expression with variable name inside the string
sample = 2
evaluate_sample = "10 * 2 / sample"
print(eval(evaluate_sample)) 

# Printing a string
print_exp = 'print("10 + 17")'
eval(print_exp)

# Another example
evaluate_sample = "10 + 17"
print(eval(evaluate_sample))


## Output
>`10`
> 
>`10 + 17`
>
>`27`

The first print statement returned the result of the expression **$10 * 2 / sample$**. The second print statement returned the expression in the string while the third print statement returned the sum of the expression in the string.

## Conclusion
The `eval()` method is not considered secure because it allows the users to execute arbitrary Python code.

However, it is useful when you want to operate Python expressions without the hassle of creating your own expressions evaluator from scratch.  


What is the eval() method in Python?

The eval() method in Python parses and evaluates an expression; it has optional globals and locals parameters. Avoid using eval() for untrusted input due to security risks.