C++: Check a string for certain characters

[Cs342]

Does anyone know if it's possible to check whether a string contains a certain set of characters in a specific order? for example if i want to check if a string contains l, a and k then "black" would return positive but "kal" would return negative because it has to be in the order l, a and then k.

[fizzlesticks]

Take a look at this thread http://linustechtips.com/main/topic/324938-help-c/

[Mo5]

Does anyone know if it's possible to check whether a string contains a certain set of characters in a specific order? for example if i want to check if a string contains l, a and k then "black" would return positive but "kal" would return negative because it has to be in the order l, a and then k.

my idea is to do a for loop to go through the string and if it finds an 'l' you check if next char is an 'a' and if it is you continue and check if the char after that is an 'k'. Otherwise you just use a continue to find the next 'l'. Something like that.

 

Edit: yeah, regex would be a better solution

[LePawel]

It's C++, string has a "find" function built in, which returns the position of the character/string found.

You can use that in combination with "substr" function to resize the string to only contain remaining characters, use find again, etc.

e.g.

std::string s = "black";std::string temp = s;int position = 0;position = temp.find("l");if(position != std::string::npos){	temp = temp.substr(position,s.size());	position = temp.find("a");	if(position != std::string::npos){		temp = temp.substr(position,s.size());		position = temp.find("k");		if(position != std::string::npos){				return true;		}	}}return false; 

And to check for 3 characters in a row you just need

std::string s = "black";std::string temp = s;int position = 0;position = temp.find("lac"); // returns location of lacposition = temp.find("lak"); // returns std::string::npos

[psychot]

Regular expressions will be very useful, and should lead to a very tight and efficient solution, that will also be easier to write than using a bunch of if statements.

[LePawel]

Regular expressions will be very useful, and should lead to a very tight and efficient solution, that will also be easier to write than using a bunch of if statements.

could you provide an example, I've never got my head around them completely