Explain each step of how this C$++$ code below executes. What does each line of code do$?$

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GradeCalculator.h

$---------------------$

#ifndef $\_$GRADECALCULATOR

#define $\_$GRADECALCULATOR

#include

#include

class GradeCalculator $\{$

private:

std::map gradeMap;

double totalPoints;

int numClasses;

char minGrade;

char maxGrade;

double gpa;

public:

GradeCalculator$()$;

void collectGrades$()$;

void calculateResults$()$;

void displayResults$()$;

$\}$;

#endif

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GradeCalculator.cpp

$-------------------$

#include "GradeCalculator.h$"$

#include

GradeCalculator::GradeCalculator$()$ : totalPoints$(0\mathrm{.}0),$ numClasses$(3),$ minGrade$(\text{'}$A$\text{'}),$ maxGrade$(\text{'}$C$\text{'}),$ gpa$(0\mathrm{.}0)\{$

gradeMap $=\{\{\text{'}$A$\text{'},4\mathrm{.}00\},\{\text{'}$B$\text{'},3\mathrm{.}00\},\{\text{'}$C$\text{'},2\mathrm{.}00\}\}$;

$\}$

void GradeCalculator::collectGrades$()\{$

std::string score;

std::cout $<<$ "How many scores are you going to enter: $"<<$ numClasses $<<$ std::endl;

for $($int i $=1$; i $<=$ numClasses; i$++)\{$

std::cout $<<$ "What is class $"<<$ i $<<"$ score: $"$;

std::cin $>>$ score;

char grade $=$ score$[0]$;

totalPoints $+=$ gradeMap$[$grade$]$;

if $($grade $<$ minGrade$)\{$

minGrade $=$ grade;

$\}$

if $($grade $>$ maxGrade$)\{$

maxGrade $=$ grade;

$\}$

$\}$

$\}$

void GradeCalculator::calculateResults$()\{$

gpa $=$ totalPoints $/$ numClasses;

$\}$

void GradeCalculator::displayResults$()\{$

std::cout $<<$ "Minimum: $"<<$ minGrade $<<$ std::endl;

std::cout $<<$ "Maximum: $"<<$ maxGrade $<<$ std::endl;

std::cout $<<$ "Your GPA is: $"<<$ gpa $<<$ std::endl;

$\}$

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Source.cpp

$---------------------$

#include

#include "GradeCalculator.h$"$

int main$()\{$

GradeCalculator gc;

gc$.$collectGrades$()$;

gc$.$calculateResults$()$;

gc$.$displayResults$()$;

return $0$;

$\}$