Lexicographic Order in Multidimensional Array C++ - arrays

Question

I'm having trouble with one final task that my program should do.
Having my output character in a lexicographic order.
For example, if I input bbbaaa it should have an output of
Frequencies:
a 3
b 3
Not
Frequencies:
b 3
a 3
Can anyone help me solve this problem?
Here is my code:
#include <iostream>
#include <string>
#include <stdio.h>
#include <ctype.h>
using namespace std;
void sort(char letters[], int integers[], int size);
void swap_letters(char& first, char& second, int& int1, int& int2);
int index_of_largest(const int integers[], int start_index, int number_used);
int main(){
const int MAX_CHARS = 200;
char letters[MAX_CHARS] = {'\0'};
int integers[MAX_CHARS] = {'\0'};
int index, size = 0;
char character;
cout << "Enter text:" << endl;
cin.get(character);
character = tolower(character);
while (character!= '.' && size < MAX_CHARS){
if(isalpha(character)){
index = 0;
while (index < size){
if(letters[index] == character)
break;
else
index++;
}
if (index < size){
integers[index] = integers[index] + 1;
}
else{
letters[index] = character;
integers[index] = 1;
size++;
}
}
cin.get(character);
character = tolower(character);
}
letters[index] = tolower(letters[index]);
sort(letters, integers, size);
cout << "Frequencies:"<< endl;
for(int i = 0; i < size; i++){
cout << letters[i] << " " << integers[i] << endl;
}
return 0;
}
void sort(char letters[], int integers[], int size){
for (int i = 0; i < size -1; i++){
int j = index_of_largest(integers, i, size);
swap_letters(letters[i], letters[j], integers[i], integers[j]);
}
}
void swap_letters(char& first, char& second, int& int1, int& int2){
char temp_char = first;
first = second;
second = temp_char;
int temp_int = int1;
int1 = int2;
int2 = temp_int;
}
int index_of_largest(const int integers[], int start_index, int number_used){
int max_int = integers[start_index];
int max_int_index = start_index;
for (int index = start_index + 1; index < number_used; index++){
if (integers[index] > max_int){
max_int = integers[index];
max_int_index = index;
}
}
return max_int_index;
}

Answer 1

The problem is in function index_of_largest() where you detect the index of largest checking only integers and ignoring letters.
All goes well when all letters are with different frequencies but doesn't work when a couple two or letter are with the same frequency. In this case you should take in count letters too.
I suppose you can correct the function in this way
int index_of_largest(const int integers[], const char letters[], int start_index, int number_used){
int max_int = integers[start_index];
int max_int_index = start_index;
for (int index = start_index + 1; index < number_used; index++){
if ( (integers[index] > max_int)
|| ( (integers[index] == max_int)
&& (letters[index] < letters[max_int_index]) )){
max_int = integers[index];
max_int_index = index;
}
}
return max_int_index;
}
But I suggest you to follow the Jack's suggestion: use STL container/algorithm when you can / when is possible
p.s.: sorry for my bad English.