How to display structures Arrays in functions - c++

Question

This program is essentially supposed to count the results of random throws of a dice 100 times and count the occurrence of each face then display all of them as a histogram of asterisks. It would seem the functions could be working but i'm unable to verify because after I make my choice, nothing displays.
#include <iostream>
#include <iomanip>
#include <string>
#include <random>
#include <sstream>
using namespace std;
enum class Side {
ONE, TWO, THREE, FOUR, FIVE, SIX
};
struct Bar {
int value;
Side label;
};
//roll dice function
void rollDice( Bar h[], int n = 100);
void rollDice( Bar h[], int){
default_random_engine en;
uniform_int_distribution<> dist{1,6};
int results[] ={0,0};
for( int n; n<=100; n++){
cout << dist(en);
results[dist(en)]++;
h[n].value = results[n];
if(h[n].value == 1){
h[n].label = Side::ONE;
}
else if(h[n].value == 2){
h[n].label = Side::TWO;
}
else if(h[n].value == 3){
h[n].label = Side::THREE;
}
else if(h[n].value == 4){
h[n].label = Side::FOUR;
}
else if(h[n].value == 5){
h[n].label = Side::FIVE;
}
else {
h[n].label = Side::SIX;
}
}
};
string getHistogram(Bar h[], char c = '*');
string getHistogram(Bar h[], char c ){
stringstream ast;
for( int n; n<=100; n++){
switch (h[n].label)
{
case Side::ONE:
return to_string(c);
break;
case Side::TWO:
return to_string(c);
break;
case Side::THREE:
return to_string(c);
break;
case Side::FOUR:
return to_string(c);
break;
case Side::FIVE:
return to_string(c);
break;
case Side::SIX:
return to_string(c);
break;
default:
break;
}
}
ast << "One: " << c << endl;
ast << "Two: " << c << endl;
ast << "Three: " << c << endl;
ast << "Four: " << c << endl;
ast << "Five: " << c << endl;
ast << "Six: " << c << endl;
string output = ast.str();
cout<< output;
return output;
}
int main (){
Bar histogram[] = {
{0,Side::ONE},{0,Side::TWO}, {0,Side::THREE},
{0,Side::FOUR},{0,Side::FIVE}, {0,Side::SIX}
};
char choice;
do {
cout << "DICE ROLLING SIMULATION" << endl
<<"===============================" << endl
<< "r. Roll Dice" << endl
<< "h. Display histogram" << endl
<< "q. Quit program\n" << endl
<< "\nEnter your choice:" << endl;
// Reading a single character using the scanner
cin >> choice;
switch(choice) {
case 'r': case 'R':
rollDice(histogram, 100);
break;
case 'h': case 'H':
cout<< getHistogram(histogram, '*');
break;
case 'q': case 'Q':
cout << "Good bye\n" << endl;
break;
default:
cout << "Invalid choice\n" << endl;
}
} while(choice != 'q');
}

Answer 1

So, this code contains many different mistakes. Let's go in order.
In structBar label may be const
struct Bar {
int value;
const Side label;
};
You don't need forward declaration for function signature
In rollDice you have many unnecessary local variables and I would use mt19937 random generator. So rollDice will look like this
void rollDice(Bar h[], int count = 100) {
default_random_engine en;
uniform_int_distribution<> dist{1,6};
for( int n = 0; n <= count; n++) {
cout << dist(en) << endl;
const auto index = dist(en) - 1;
++h[index].value;
}
};
In getHistogram you have return to_string(c); in switch therefore you don't see histogram. You can delete swith because you can match index and Side. And why cycle up to 100?
string getHistogram(Bar h[], char c = '*') {
stringstream ast;
for( int n = 0; n <= 5; n++) {
const string strValue = string(h[n].value, c);
switch (h[n].label)
{
case Side::ONE: ast << "One: "; break;
case Side::TWO: ast << "Two: "; break;
case Side::THREE: ast << "Three: "; break;
case Side::FOUR: ast << "Four: "; break;
case Side::FIVE: ast << "Five: "; break;
case Side::SIX: ast << "Six: "; break;
}
ast << strValue << '(' << h[n].value << ')' << endl;
}
return ast.str();
}
In main function you have to clear histogram before next rollDice
case 'r': case 'R':
for (Bar& b : histogram) {
b.value = 0;
}
rollDice(histogram, 100);
break;
Full version
#include <iostream>
#include <iomanip>
#include <string>
#include <random>
#include <sstream>
using namespace std;
enum class Side {
ONE, TWO, THREE, FOUR, FIVE, SIX
};
struct Bar {
int value;
Side label;
};
void rollDice(Bar h[], int count = 100) {
default_random_engine en;
uniform_int_distribution<> dist{1,6};
for( int n = 0; n <= count; n++) {
cout << dist(en) << endl;
const auto index = dist(en) - 1;
++h[index].value;
}
};
string getHistogram(Bar h[], char c = '*') {
stringstream ast;
for( int n = 0; n <= 5; n++) {
const string strValue = string(h[n].value, c);
switch (h[n].label)
{
case Side::ONE: ast << "One: "; break;
case Side::TWO: ast << "Two: "; break;
case Side::THREE: ast << "Three: "; break;
case Side::FOUR: ast << "Four: "; break;
case Side::FIVE: ast << "Five: "; break;
case Side::SIX: ast << "Six: "; break;
}
ast << strValue << '(' << h[n].value << ')' << endl;
}
return ast.str();
}
int main (){
Bar histogram[] = {
{0, Side::ONE},
{0, Side::TWO},
{0, Side::THREE},
{0, Side::FOUR},
{0, Side::FIVE},
{0, Side::SIX}
};
char choice;
do {
cout << "DICE ROLLING SIMULATION" << endl
<<"===============================" << endl
<< "r. Roll Dice" << endl
<< "h. Display histogram" << endl
<< "q. Quit program\n" << endl
<< "\nEnter your choice:" << endl;
// Reading a single character using the scanner
cin >> choice;
switch(choice) {
case 'r': case 'R':
for (Bar& b : histogram) {
b.value = 0;
}
rollDice(histogram, 100);
break;
case 'h': case 'H':
cout << getHistogram(histogram, '*') << endl;
break;
case 'q': case 'Q':
cout << "Good bye\n" << endl;
break;
default:
cout << "Invalid choice\n" << endl;
}
} while(choice != 'q');
}