Earlier, we saw how to parse a String to an Int or float in Python. Now, we want the opposite. How to do it?
In Python, there are two ways to transform any value into a string: the functions repr () and str ().
The str () function is used to create value representations that people can understand. The repr () function is used to create values that the Python interpreter can use.
For most values, such as integers, lists, and dictionaries, they have the same representation when using any of the functions. Floats and Strings, on another hand, are represented in different ways when using one or other function.
The only difference between the two functions is the way they present the values? As a matter of fact, no. Let’s look this subject a little deeper.
Main differences between str () and repr () in Python
At the Python official documentation, we read that repr () and str () are used to “represent” an object. The str () is considered an “informal” representation. The repr () function would be the “formal” representation.
Below we have some examples where can be seen some of these differences:
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s = 'Hello, world.' str(s) Hello world program repr(s) Hello world program str(1.0/7.0) '0.142857142857' repr(1.0/7.0) '0.14285714285714285' |
This difference between the returned values in the above examples can be verified within the system. The default return value of repr () function to an object can be called as an argument within the eval () function. The return of eval() will be a valid object. We can see this in the example below:
| 1 | >>> Y = ‘string’ |
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>>> Repr (y)
” ‘String'” >>> Y 2 = eval (repr (y)) >>> Y == y2 True |
The return of the str () function is shown as not valid. Example below:
| 1 | >>> Y = ‘string’ |
| 2
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>>> Str (y)
‘String’ >>> Eval (str (y)) Traceback (most recent call last): File “<stdin>”, line 1, in <module> File “<string>”, line 1 the string ^ SyntaxError: unexpected EOF while parsing |
Thus, the “formal” representation of the object can be called by the eval () function, and must return the same object, if applicable.
Why use the “informal” representation str () in Python?
It returns a briefer response of the value of the object. Complex objects, with several arguments, repr () function returns a value difficult to be analyzed. If we are only looking for a “quick view”, the best thing to use is the str () function.
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