# Python complex() — A Useless Python Feature?

The Python `complex()` method returns a complex number object. You can either pass a string argument to convert the string to a complex number, or you provide the real and imaginary parts to create a new complex number from those.

This article shows you how to use Python’s built-in `complex()` constructor. You’ll not only learn how to use it—but also why it is useless and what you should do instead in newer Python versions.

## Usage

Learn by example! Here are some examples of how to use the `complex()` built-in function:

```>>> complex(1, -2)
(1-2j)
>>> complex(2, -1)
(2-1j)
>>> complex(2, 2)
(2+2j)
>>> complex(1)
(1+0j)
>>> complex(2)
(2+0j)
>>> complex('42-21j')
(42-21j)```

## Syntax Complex()

You can use the `complex()` method with three different argument lists.

```Syntax:
`complex(real)         # Imaginary Part is 0j`
`complex(real, img)    # Both real and imaginary part are given`
`complex(string)       # String has format 'x+yj' for real part x and imaginary part y. ````

## Interactive Shell Exercise: Understanding Complex()

Consider the following interactive code:

Exercise: Guess the output before running the code.

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## How to Create Complex Number Without complex()

Interestingly, you don’t need the `complex()` constructor to create a complex number! Instead, newer version of Python have built-in complex number support—just use the the syntax `x+yj` for real part `x` and imaginary part `y` to obtain a complex number.

```a = 1+1j
b = 4+42j
c = 0+0j

print('Complex Numbers:')
print(a, b, c)

print('Types:')
print(type(a), type(b), type(c))
```

The output is:

```Complex Numbers:
(1+1j) (4+42j) 0j
Types:
<class 'complex'> <class 'complex'> <class 'complex'>```

## Summary

The Python `complex()` method returns a complex number object. To create a complex number:

• Pass a string argument to convert the string to a complex number, or
• Provide the real and imaginary parts to create a new complex number from those.

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