How to quicksort user input

Question

The question is rather simple but the more I search the more confused I get. I'm supposed to quicksort a variable from the struct code I've written. However, I don't understand how I'm supposed to quicksort a variable like em.fName if it's changed every iteration of the loop. Every example I look up seems to sort int variables or predefined character arrays. Could some one point me in the right direction where to start and/or give an example in C? Thanks, greatly appreciate it. I've posted the full code here since I didn't want to clutter the post.

    typedef struct EmployeeRecord
    {
    STR21 lName;
    STR11 fName;
    char fullName[33];
    float hrs;
    float pay;
    float dfr;
    float gross;
    float ft;
    float st;
    float ssit;
    float net;

    } EmployeeRecord;

int main(void)
{
    EmployeeRecord em;

    do
    {
        counter++;
        em.dfr = em.ft = em.st = em.ssit = em.gross = em.hrs = em.pay = em.net = ovrtHrs = 0; //initalized to 0 and then changed by function if greater than 0
        printf("Please enter your FIRST name: ");
        scanf("%s",fName);
        printf("Please enter your LAST name: ");
        scanf("%s",lName);
        printf("Enter your payrate: ");
        scanf("%f",&em.pay);
        printf("Please enter your total hours: ");
        scanf("%f",&em.hrs);
        printf("Please enter the amount of deferred earnings: ");
        scanf("%f",&em.dfr);

        strcpy(fullName,lName); // combine last + ", " + first into full
                strcat(fullName,", ");
                strcat(fullName,fName);

        payTotal = payTotal + em.pay;
        dfrTotal = dfrTotal + em.dfr;

        em.gross = grossModule(&em.hrs,em.pay,&ovrtHrs); // call 3.4
        CalculateTaxes(&em.gross,&em.dfr,&em.ft,&em.st,&em.ssit); // call 3.0
        em.net = netModule(&em.gross,&em.ft,&em.st,&em.ssit); // cal 3.5

        hoursTotal = hoursTotal + em.hrs;
        overtimeTotal = overtimeTotal + ovrtHrs; // TOTALS
        grossTotal = grossTotal + em.gross;
        stateTotal = stateTotal + em.st;
        ssiTotal = ssiTotal + em.ssit;
        netTotal = netTotal + em.net;
        fedTotal = fedTotal + em.ft;

        fprintf(myreport,REPORTCOLUMNFORMATS,em.fullName,em.pay,em.hrs,em.gross,em.ft,em.ssit,em.net);
        fprintf(myreport,REPORTCOLUMNFORMATS3,ovrtHrs,em.st,em.dfr);


        printf("Would you like to continue, y/n? \n");
        scanf("%s",&ask);

    }while(ask == 'y' || ask == 'Y');

Answer 1

Here are some pointers:

1. You are only reading one EmployeeRecord and then it gets overwritten, if you want to sort them you have to save them all. You could work with realloc to dynamically change the size of the reserved space or keep it simple:

    EmployeeRecord employees[100]; // will fail if more than 100 employees are added ... // after em is complete: employees[counter++] = em; // remove the other counter++ 

2. Sorting taken from wikibooks.org and replaced the pointers by normal int, working with the index instead of pointer math (easier to understand) and added compare function which you will have to fill:

    void swap(int a, int b) { EmployeeRecord tmp = employees[a]; employees[a] = employees[b]; employees[b] = tmp; } int compare(int a, int b) { // return -1 if employees[a] comes before employees[b] // return 1 if employees[a] comes after employees[b] // return 0 "if they have the same order" // (stable algorithms eg mergesort won't change the order of those) } void quicksort(int begin, int end) { int ptr; int split; if (end - begin <= 1) return; ptr = begin; split = begin + 1; while (++ptr <= end) { if (compare(ptr, split) > 0) { // sorts ascending swap(ptr, split); ++split; } } swap(begin, split - 1); quicksort(begin, split - 1); quicksort(split, end); } 

3. Sort and create the report after the user decided to not continue any more.