Find Lowest Character Using Binary Search Using C Language

Question

Example TestData.txt

Aquos|5@10000 
Chitato|10@9500
Chili|20@4000

Output I want(using Quick Sort) report (by subtotal):

A5-120-0|Aquos|5@10000=50000
C5-120-1|Chili|20@4000=80000
A7-504-0|Chitato|10@9500=95000
Total Price = 225000

[a] [b] - [c] - [d]
[a] Got From The Lowest Character in Name
[b] Got From The Length of Character (Take The Last Digit)
[c] Got From Factorial of The Name Length (Output First 3 Digits)
[d] Got From The Counter of The Same Number Of Factorial [c]

I already code it, but, I confused how to implement Binary Search to get The Lowest Character in Name.

Here is my Code (I confused On FindA Function):

#include <stdio.h>
#include <string.h>
#include<ctype.h>

struct sales{
    char item[20];
    int quantity, price,subtotal;
    char a;
    int b,c,d;
};

void quickSort(struct sales data[],int first, int last)
{
    int pivot, i, j;
    char tempItem[25];
    int temp;
    if(first < last){
        i = first;
        j = last;
        pivot = first;
    while(i<j)
    {
        while(data[i].subtotal <= data[pivot].subtotal && i<last)
        {
            i++;
        }       
        while(data[j].subtotal > data[pivot].subtotal)
        {
            j--;
        }
        if(i<j)
        {
            temp = data[i].subtotal;
            data[i].subtotal = data[j].subtotal;
            data[j].subtotal = temp;
            temp = data[i].quantity;
            data[i].quantity = data[j].quantity;
            data[j].quantity = temp;
            temp = data[i].price;
            data[i].price = data[j].price;
            data[j].price = temp;
            strcpy(tempItem,data[i].item);
            strcpy(data[i].item,data[j].item);
            strcpy(data[j].item,tempItem);
        }
    }
        temp = data[pivot].subtotal;
        data[pivot].subtotal = data[j].subtotal;
        data[j].subtotal = temp;
        temp = data[pivot].quantity;
        data[pivot].quantity = data[j].quantity;
        data[j].quantity = temp;
        temp = data[pivot].price;
        data[pivot].price = data[j].price;
        data[j].price = temp;
        strcpy(tempItem,data[pivot].item);
        strcpy(data[pivot].item,data[j].item);
        strcpy(data[j].item,tempItem);

        quickSort(data,first,j-1);
        quickSort(data,j+1,last);
    }
}

char findA(char item[])
{
    char lowest;
    int i;
    lowest = toupper(item[0]);
    i=1;
    while(item[i]!='\0')
    {
        if(toupper(item[i]) < lowest)
            lowest = toupper(item[i]);
        i++;
    }
    return lowest;
}

int findB(char item[])
{
    int length;
    length = strlen(item);
    length = length%10;
    return length;
}

int findC(int length)
{
    int fact = 1,i;
    for(i=1;i<=length;i++)
    {
        fact = fact * i;
    }
    char temp[10];
    sprintf(temp,"%d",fact);
    int hundreds = temp[0] - '0';
    int tens = temp[1] - '0';
    int ones = temp[2] - '0';
    int num;
    num = hundreds*100 + tens*10 + ones;
    return num;
}

int findD(struct sales data[],int i)
{
    int count,j,currentC;
       count = 0;
        j=0;
        while(j<i)
        {
            if(data[i].c == data[j].c)
                count++;
            j++;
        }
        return count;
}

int main()
{
    int count,i,j,n,total = 0;
    FILE *input = fopen("TestData.txt","r");
    struct sales data[100];
    n = 0;
    while(fscanf(input,"%[^|]|%d@%d\n", data[n].item,&data[n].quantity,&data[n].price) != EOF)
    {
        data[n].subtotal = data[n].quantity * data[n].price;
        total = total + data[n].subtotal;
        n++;
    }
    fclose(input);

    quickSort(data,0,n-1);

    for(i=0;i<n;i++)
    {
        data[i].a = findA(data[i].item);       
        data[i].b = findB(data[i].item);       
        data[i].c = findC(strlen(data[i].item));
        data[i].d = findD(data,i);       
        printf("%c%d-%d-%d|%s|%d@%d=%d\n",data[i].a,data[i].b,data[i].c,data[i].d,data[i].item,data[i].quantity,data[i].price,data[i].subtotal);
    }
    printf("Total Price = %d\n",total);
    return 0;
}

https://pastebin.com/fJQaFdqY