Validate input using regex

Question

I honestly don't know what I am doing wrong. I have checked the regex expression in http://regexpal.com/ and it works just fine

here is my code:

std::string text = "1.98";
std::regex regex_number("((\b[0-9]+)?\.)?[0-9]+\b");  
bool isValid = std::regex_match(text, regex_number);

It should be valid for integers and doubles Ex:

• 1.2
• 1
• 1.99
• 0.6

Not valid for

• aa
• dd
• 1.2h
• 1,6

I get Non Valid text for everything.

Answer 1

您忘了在字符串文字中转义反斜杠：

std::regex regex_number("((\\b[0-9]+)?\\.)?[0-9]+\\b"); 

Answer 2

You also stuck that first word delimiter in the wrong spot. It should be outside the optional sections:

"\\b(([0-9]+)?\\.)?[0-9]+\\b"

(Sorry for the additional answer; I still don't have the rep to add comments.)