Thread: Erase characters in std::string

  1. #1
    Registered User
    Join Date
    May 2006
    Posts
    35

    Erase characters in std::string

    All i'm trying to do is erase the first occurance of a character in a std::string.

    str::erase(iterator) takes an iterator as an argument, but std::find() returns size_type.

    This is the best i can come up with.
    There's has got to be an easier way right?

    Code:
    int main(int argc, char *argv[])
    {
        string str = "seller";
        char c = 'l';
       	string::iterator pos;
       	pos = str.begin();
    
            //seek first occurence
       	while(pos != str.end() && *pos !=
     c)
       	          pos++;
        
        //erase first occurence 
        str.erase(pos);
        
    	
    	cout << str << endl;
    	
        return 0;
    }

  2. #2
    (?<!re)tired Mario F.'s Avatar
    Join Date
    May 2006
    Location
    Angola
    Posts
    8,232
    Code:
    str.erase(std::find(str.begin(), str.end(), 'c'));
    or

    Code:
    std::string::iterator found = std::find(str.begin(), str.end(), 'c');
    if( found != str.end())
        str.erase(found);
    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  3. #3
    Registered User
    Join Date
    Jan 2005
    Posts
    7,359
    You can do begin() + loc to get an iterator where loc is the size_type location of the character returned by find.

    Mario F., as the OP stated, find returns an index not an iterator.

  4. #4
    (?<!re)tired Mario F.'s Avatar
    Join Date
    May 2006
    Location
    Angola
    Posts
    8,232
    Ah gotcha. Skipped that. Sorry.

    Well it's just a matter of replacing std:string::iterator with size_type

    EDIT: Unless the erase function is not overloaded for size_type...
    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  5. #5
    (?<!re)tired Mario F.'s Avatar
    Join Date
    May 2006
    Location
    Angola
    Posts
    8,232
    Well... actually...

    If find() returns a size_type is because you are using the string::find() member function, not the algorithm one. Use the algorithm one defined under <algorithm>.

    http://www.cppreference.com/cppalgorithm/find.html
    Originally Posted by brewbuck:
    Reimplementing a large system in another language to get a 25% performance boost is nonsense. It would be cheaper to just get a computer which is 25% faster.

  6. #6
    Registered User
    Join Date
    May 2003
    Posts
    1,619
    Quote Originally Posted by Daved
    Mario F., as the OP stated, find returns an index not an iterator.
    He's using std::find, not std::string::find.
    You ever try a pink golf ball, Wally? Why, the wind shear on a pink ball alone can take the head clean off a 90 pound midget at 300 yards.

  7. #7
    Registered User
    Join Date
    Jan 2005
    Posts
    7,359
    Right. The OP mentioned std::find as well, but my guess is that was a typo (see similar typo with str::erase). Either way, I would use the member function version and add the size_type to the begin() iterator as I showed. Prefer the member function over the generic algorithm in general, and the addition to the iterator isn't a big enough deal to outweigh that advice in this case.

    >> Unless the erase function is not overloaded for size_type.
    The other option is s.erase(s.find(...), 1). The 1 is to indicate a single character at the specified location. This might actually be the best option.

  8. #8
    Registered User
    Join Date
    May 2006
    Posts
    35
    Yeah, those were typos....i do it all the time with 'string' and 'str'....

    i'm liking the begin()+index idea..haven't tried it yet, but i'm sure it works..

    thanks Dave .... ("good effort " to the rest of you )

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. A development process
    By Noir in forum C Programming
    Replies: 37
    Last Post: 07-10-2011, 10:39 PM
  2. erase all characters in a character array?
    By diddy02 in forum C Programming
    Replies: 4
    Last Post: 11-20-2008, 04:30 PM
  3. Replies: 10
    Last Post: 07-10-2008, 03:45 PM
  4. help with text input
    By Alphawaves in forum C Programming
    Replies: 8
    Last Post: 04-08-2007, 04:54 PM
  5. Debugging help
    By cuddlez.ini in forum C++ Programming
    Replies: 3
    Last Post: 10-24-2004, 07:08 PM