CODEWITHSUNDEEP
python
masiewpao
masiewpao

Reputation: 309

Why are certain hexadecimal escape characters not displayed in python 3 unless the print statement is used?

I am learning about strings and bytestrings in python. I don't understand why certain hexadecimal escape sequences are displayed in \XNN form and some are not?

s = 'A\x31\tC'
s1 = 'A\x00B\tC'

In this case, when I type s1 into the console, it prints the exact string of characters within the quotes,'A\x00B\tC', but when I type s into the console, it prints 'A1B\tC'. It is only when I print s1 that the screen shows 'AB C'. I don't understand why certain escape characters are shown and others are not? And why does it then show when you print them?

Cheers

Upvotes: 1

Views: 500

Answers (2)

Andrei Cioara
Andrei Cioara

Reputation: 3664

http://www.asciitable.com/

If you look at the ASCII table, you would see that some characters are printable, while others are not.

In particular, \x31 == 1 (Hexadecimal 31 == Decimal 49 == ASCII Character 1.

On the other hand \x00 is not printable. It represents the null terminator (or \0)

>>> '\x31' == '1'
True
>>> '\x00' == '\0'
True

A more interesting question is: Why does \x31 get converted to 1, \x09 gets converted to a \t, while \x00 is not converted to \0. That I don't know.

Upvotes: 2

jfowkes
jfowkes

Reputation: 1565

When you type name into the interpreter, it is using the result of calling repr on that name. Since \x31 can be represented as 1, it uses that. Since \x00 cannot be represented as a printable character, it falls back to using the hex escape notation.

Note that:

>>> '\x31' == '1'
True

So the result of repr is valid.

Upvotes: 2

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