C++ special characters in a regular expression

Question

I have to parse a regular expression which can contain special symbols such as \s and \d. The problem is, I can't distinguish the \ when i am parsing the expression, I mean '\s' == 's', therefore I cannot distinguish between special character and basic character. How can I solve this?

No. I have a given expression: a\sb which will be different from asb, but i cannot catch the single *\* to parse it properly — Michaela
– Michaela, Commented Jan 31, 2017 at 10:42

O'Neil · Accepted Answer · 2017-01-31 11:25:47Z

2

Raw string literals since C++11 can help you to improve the readability:

"a\\sb" // matches: a[whitespace]b "a\\\\sb" // matches: a\sb

becomes:

R"(a\sb)" // matches: a[whitespace]b R"(a\\sb)" // matches: a\sb

edited Jan 31, 2017 at 11:25

answered Jan 31, 2017 at 11:03

O'Neil

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1 Comment

Martin Bonner supports Monica Over a year ago

I think your second examples should read "matches: a\\sb" - note the "s" before the "b"

MSalters · Accepted Answer · 2017-01-31 10:52:26Z

You're confusing user input and character literals. You catch the user input \ by comparing all input characters with the character literal '\\'.

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