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POwhy is pointer address changing on return?
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  1. POwhy is pointer address changing on return?
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    copied!<p>I'm working on homework, and I'm having a weird problem I'm hoping someone can help me out with. I have a function in the middle of my code:</p> <pre><code>Token scheme::addScheme(vector &lt;Token&gt; toAdd) { //Check if scheme is valid Token answer = isSchemeValid(toAdd); if (answer.retType() != "ok") { return answer; } identifierList * arrow = new identifierList(&amp;(toAdd.at(0)), NULL); idList = arrow; for (int i = 2; i &lt; toAdd.size()-1; i++) { (*arrow).id = &amp;(toAdd.at(i)); (*arrow).next= new identifierList(&amp;(toAdd.at(0)), NULL); arrow = (*arrow).next; } *id = toAdd.at(0); openParen = '('; closeParen = ')'; return Token("ok", "ok", 0); } </code></pre> <p>This code does everything I need it to do, except for the very end. It correctly sets all the variables to what I need them to be. Here's where it doesn't work: I run it step by step and I see that right after running the very last line return Token("ok", "ok", 0); the values of idList change from legitimate values to crazy ones (for example, the first id in the idList's line number changes from 2 to -17891602.</p> <p>this might make more sense if I post the header for what a identifierList and Token consist of: Token: #pragma once using namespace std; #include #include #include #include #include "datalogProgram.h"</p> <pre><code>enum state {COMMA, PERIOD, Q_MARK, LEFT_PAREN, RIGHT_PAREN, COLON, COLON_DASH, MULTIPLY, ADD, SCHEMES, FACTS, RULES, QUERIES, ID, STRING, COMMENT, WHITESPACE, UNDEFINED, ENDOFFILE, START}; class Token { friend class datalogProgram; public: int lineNumber; string type; string value; Token(string inType, string inValue, int inLineNum); void route(state inState, string inValue, int inLineNum); string retType(); string retValue(); //A list of a bunch of functions that don't matter here. }; </code></pre> <p>And an identifierList:</p> <pre><code>class identifierList { friend class scheme; public: Token * id; identifierList * next; identifierList(Token * inId, identifierList * inNext); }; </code></pre> <p>I don't get it- why are any variables changing when all I'm doing is returning from a function?</p>
 

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