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POC++ Passing map from object
 

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    <p>I am building a simple program to 'learn as I go', this program takes a couple of text files and processors them, each line of the first text file is information about a person, and for each line an Object (of type Student (see below)) is created and added to a vector. Within the Student objects is a map that stores that students marks. I have a function within the student class that returns the map when called (or at least thats what im trying to do). Currently this function is:</p> <pre><code>marksType Student::printMarks(){ return marks; } </code></pre> <p>(Where <code>marksType = std::map&lt;string, float&gt;</code>) and <code>marks</code> is the map of type <code>marksType</code>.</p> <p>Then in my main function I have:</p> <pre><code>Student a = *qw; studmarks = a.printMarks(); for (std::map&lt;string, float&gt;::iterator iter = studmarks.begin(); iter != studmarks.end(); iter++){ cout &lt;&lt; "TEST" &lt;&lt; endl; } </code></pre> <p>Where qw is a pointer to a student object and studmarks is of type <code>map&lt;string, float&gt;</code></p> <p>The issue is that the cout doesn't get called so the iterator seems to skip (but the student object does have items in the marks map).</p> <p>Heres the complete Student class</p> <pre><code>#include "Student.h" using namespace std; typedef std::map&lt;string, float&gt; marksType; Student::Student(const string &amp;name, int regNo) : Person(name){ marksType marks; this-&gt;regNo = regNo; } int Student::getRegNo() const{ return regNo; } void Student::addMark(const string&amp; module, float mark){ pair&lt;marksType::iterator,bool&gt; check; check = marks.insert (pair&lt;string,float&gt;(module,mark)); if (check.second==false){ marks[module]=mark; } } float Student::getMark(const string &amp;module) const throw (NoMarkException){ if (marks.find(module) != marks.end()){ return marks.find(module)-&gt;second; } else throw NoMarkException(); } float Student::getAverageMark() const throw (NoMarkException){ if (!marks.empty()){ float avgmark = 0; for (marksType::const_iterator avgit=marks.begin(); avgit!=marks.end(); ++avgit){ avgmark = avgmark + avgit-&gt;second; } avgmark = avgmark/marks.size(); return avgmark; } else throw NoMarkException(); } marksType Student::printMarks(){ return marks; } </code></pre> <p>Oh and below is the part of the main function that adds marks to the students,</p> <pre><code>for (vector&lt;Student&gt;::iterator it = students.begin(); it != students.end(); ++it){ Student b = *it; if (regno == b.getRegNo()){ found = true; b.addMark(module, mark); } } </code></pre> <p>I know this works because when I use the getMark function it does work.</p>
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    1. USZac Powell
    1. USZac Powell
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    1. COGeneral note, remember that both the lines `Student a = *qw; studmarks = a.printMarks();` involve copies, and do not deal with the original objects any more.
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      1. USKarthik T
    2. COYes thats not an issue, im not editing the data (there are other functions to do this) just need to access the data to print it out etc
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      1. USZac Powell
    3. CORegardless something to keep in mind, since these are probably not classes that are meant to be copied..
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      1. USKarthik T
 

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