Thread: Understanding C++ Online References

  1. #1
    Join Date
    Jan 2005

    Understanding C++ Online References

    That may be a poorly worded title, but this is what I am confused about. The only online reference I use for C++ is this website:

    When I look functions up, it doesn't seem to tell me everything that is available. For instance, when looking the transform function here:

    this is the prototype:

    #include <algorithm>
    iterator transform( iterator start, iterator end, iterator result, UnaryFunction f );
    iterator transform( iterator start1, iterator end1, iterator start2, iterator result, BinaryFunction f );
    What exactly is UnaryFunction f? I know that a unary function is something that operates on only one member (unlike binary operators addition, multiplication, etc). From other code, I have seen that tolower and toupper work there when operating on strings, but what else is available?

    For a day or two I messed around with Windows programming and when searching the MSDN is seemed to explicitly say what options could be placed there. Are there any sites like that are a general C++ reference site and not specific to windows programming?

    It seems like the biggest hurdle to programming is understanding the documentation. There certainly isn't a lack of it out there. It's just getting to the point where it all makes sense and you can understand it.

    Check this code out:

    // An improved version of the program! ^_^ Good mood...
    #include <iostream>
    #include <string>
    int main (void) 
       std::string answer = "twenty";
       std::cout << "How many apples did I buy? (word answers):";
       std::cin >> answer;
       transform(answer.begin(), answer.end(), answer.begin(), tolower);
       if(answer != "twenty")
           std::cout << "Sorry, you're wrong\n";
           std::cout << "Yes, that's correct\n";
    One more quick question.
    Why does this code work without me including the algorithm header? Is it automatically included with the string header?

    Thank you.

  2. #2
    Code Goddess Prelude's Avatar
    Join Date
    Sep 2001
    >What exactly is UnaryFunction f?
    A template parameter name. It basically means that a function or function object that can take one argument is expected.

    >Are there any sites like that are a general C++ reference site and not specific to windows programming?
    I'm not sure what you mean by "like that", but I prefer Dinkumware's reference when I don't have the standard on me.

    >Is it automatically included with the string header?
    Or the iostream header, but you shouldn't rely on that.
    My best code is written with the delete key.

  3. #3
    Ethernal Noob
    Join Date
    Nov 2001
    I find that reference site to be incomplete anyway. Check out see if it works for you. While it's not as orgaized into subsections as the other one, it has much more information.

  4. #4
    Registered User
    Join Date
    Mar 2006
    The STL operates on a higher level of abstraction; it makes use of concepts. Eg. BinaryFunction is simply a function which takes two arguments of some type and returns a value. It doesn't even need to be a normal function; you can pass a function pointer or even object.

    The code snippet will not or should not compile:
    <algorithm> is not included
    transform() is in std::
    #include <stdio.h>
    void J(char*a){int f,i=0,c='1';for(;a[i]!='0';++i)if(i==81){
    /3*3+f/3*9+f%3]==c||a[i%9+f*9]==c||a[i-i%9+f]==c)goto e;a[i]=c;J(a);a[i]
    ='0';e:;}}int main(int c,char**v){int t=0;if(c>1){for(;v[1][
    t];++t);if(t==81){J(v[1]);return 0;}}puts("sudoku [0-9]{81}");return 1;}

  5. #5
    Frequently Quite Prolix dwks's Avatar
    Join Date
    Apr 2005
    I also find that isn't the best. I usually use google, not a particular reference.

    Man pages are often a good reference. Googling for "man function" often works.

    Also see this:

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell

    Other boards: DaniWeb, TPS
    Unofficial Wiki FAQ:

    My website:
    Projects: codeform, xuni, atlantis, nort, etc.

  6. #6
    Join Date
    Jan 2005
    Thanks for the help.

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