Author: Joshua Haglund
Date: 13:23:25 01/08/03
Go up one level in this thread
On January 08, 2003 at 06:48:48, David Rasmussen wrote:
>On January 08, 2003 at 03:22:17, Joshua Haglund wrote:
>
>I am not even going to begin summing up all the problems there is with this. I
>suggest you learn more about C++ before you try to make a chess engine. I
>suggest you read "Accelerated C++" by Koenig and Moo, one of the very best C++
>books out there.
>
>But read below:
>
>>#include <iostream>
>>#include <string>
>>using namespace std;
>>
>>void getMoves(string);
>>
>
>Here you are declaring a function getMoves which takes a string.
>
>>int main() {
>>
>>string moves[31] = {"e2e4", "e2e3", "d2d4", "d2d3",
>> "c2c4", "c2c3", "b2b4", "b2b3",
>> "g2g3", "g2g4", "a2a3", "a2a4",
>> "f2f3", "f2f4", "h2h3", "h2h4",
>> "e3e4", "d3d4", "c3c4", "a3a4",
>> "b3b4", "f3f4", "g3g4", "h3h4",
>> "e4e5", "e5e6", "e6e7", "e7e8R",
>> "e7e8Q", "e7e8B", "e7e8N"};
>>
>>getMoves(moves[31]);
>>
>
>Here you are calling a function called getMoves that takes a string. Although,
>you are calling it with moves[31] which is undefined. The last valid entry of
>your array is moves[30].
>string moves[31] = ...
>declares an array of 31 elements, from element 0 to element 30. So the call is
>wrong anyway.
>
>>
>>
>>return 0;
>>}
>>
>>void getMoves(string m[31])
>
>Here you are declaring and defining a function called getMoves which takes an
>array of strings. This function is not called from anywhere.
>
>>{
>>
>>
>>cout << m[31] << endl;
>>
>
>Here you are streaming out the 31th element of the array you took as an
>argument, which only had 31 elements, from 0-30, that is, it is undefined.
>
>>}
>>
>
>You have still not _defined_ the function you _declared_ above, the one that
>took a string. You have only defined another totally unrelated function that
>took an array of string.
>
>>I get this error. I don't know what this means.
>>Is this error saying it's not possible to pass the string by value?? Hmmm
>>
>
>
>The linker is complaining that you declared a function that took a string, you
>called this function, but you never defined it, or linked with something that
>defined it.
>
>In summary:
>You declared a function that took a string, called it, but never defined it.
>Instead you defined a function that took an array of string, which you never
>used. The simplest way of getting your code to compile is to change the
>
>void getMoves(string m[31])
>
>to
>
>void getMoves(string m)
>
>now it compiles, although it's probably not doing what you thought it would
>(because it's undefined).
>
>So change also
>
>cout << m[31] << endl;
>
>to
>
>cout << m << endl;
>
>and the program probably behaves as you intended.
>
>I really suggest you read up on C++ before making a chess engine:
>
>http://www.acceleratedcpp.com/
>
>/David
Thanks for your help and it does compile after those changes, but it crashes
because I made a typo with: getMoves(moves[31]); it should be 30 since 31
doesn't exsist; it crashes.
Thanks for the advice with Accelerated C++. I will look into it.
Thanks,
Joshua
toneewa@yahoo.com
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