Python’s built-in str(x) function converts the object x to a string using the x.__str__() method or, if non-existent, the repr(x) built-in function to obtain the string conversion.
Syntax str()
Syntax:
str(object)
# --> Most common case: convert an object to a string
str(object=b'', encoding='utf-8', errors='strict')
# --> Not so common case: Converts a bytes or bytearray to a string by calling the method bytes.decode()| Arguments | object | Object to be converted to a string. If empty or not provided, returns the empty string ''. |
encoding | (Optional) Only if object is a bytes object. The encoding used—for example ASCII or UTF-8. | |
errors | (Optional) One of the options: 'strict', 'replace', or 'ignore'. See table below for more details. | |
| Return Value | string | Returns a string value as defined by the object.__str__() method. |
Video str()
Usage Examples str()
The following code shows you how to use the str(x) function on how to convert an object to a string:
>>> str(42)
'42'
>>> str(3.14)
'3.14'
>>> str([1, 2, 3])
'[1, 2, 3]'
>>> str({'Donna': 33, 'Harvey': 44})
"{'Donna': 33, 'Harvey': 44}"The following code shows you how to use bytes or bytearray inputs as object argument.
>>> str(b'hello') "b'hello'" >>> str(b'hello', encoding='UTF-8') 'hello' >>> str(b'hello', encoding='UTF-8', errors='ignore') 'hello'
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How to Implement Your Own String Representation for a Custom Object
To implement your own string representation when using the str(object) function on your custom object, overwrite the object.__str__() method when defining the class and return the desired string representation of the given object. If no __str__() method is defined, Python uses the __repr__ method as a fallback that’s implemented per default for any object.
class Car:
def __init__(self, color, brand):
self.color = color
self.brand = brand
def __str__(self):
return 'Your car has color ' + self.color + ' and brand ' + self.brand
def __repr__(self):
return '123'
porsche = Car('black', 'porsche')
tesla = Car('silver', 'tesla')
print(str(porsche))
print(str(tesla))
The output is:
Your car has color black and brand porsche Your car has color silver and brand tesla
Note how the __str__ method takes precedence over the __repr__ method. But if you skip the definition of the __str__ method, it’ll take the string returned by the __repr__ method:
class Car:
def __init__(self, color, brand):
self.color = color
self.brand = brand
def __repr__(self):
return '123'
porsche = Car('black', 'porsche')
tesla = Car('silver', 'tesla')
print(str(porsche))
print(str(tesla))The output now is:
123 123
[Table] 7 Different “errors” Arguments of str()
You can use the following error handlers in the str() function when using a bytes or bytearray input argument.
| Value | Meaning |
|---|---|
'strict' | (Default) Raise UnicodeError |
'ignore' | If data input would cause an error, ignore it and continue without notice. |
'replace' | Replace with replacement marker U+FFFD for decoding codecs, and '?' on encoding. |
'xmlcharrefreplace' | Replace with XML character reference for encoding. |
'backslashreplace' | Replace with escape sequences. |
'namereplace' | Replace with \N{...} escape sequences for encoding. |
'surrogateescape' | Replace byte with individual surrogate code ranging from U+DC80 to U+DCFF. |
You can find more details about these error handlers at the source here.
Summary
Python’s built-in str(x) function converts the object x to a string using the x.__str__() method or, if non-existent, the repr(x) built-in function to obtain the string conversion.
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