Question

I am new to C programming and am trying to quick sort an array of records. I’m not sure if I am sending the Record to the function properly but my error is

error: conversion from “TaxRecord*” to non-scalar type “TaxRecord” requested
error: no match for “operator<” in “*(table + ((unsigned int)(((unsigned int)left) * 104u))) < pivot”

void qsort(TaxRecord table,int start,int finish);

qsort(theEmployees[i],0,i);

void qsort(TaxRecord table[],int start,int finish) {
    int left = start,
    right = finish;
    TaxRecord pivot = table[((start+finish)/2)];
    TaxRecord temp = table;

    while (left < right) {
        // find left candidate
        while (table[left]  < pivot)
            left++; 
        // find right candidate 
        while (table[right] > pivot)
            right--; 
        if (left <= right) {
            int temp = table[left];
            table[left] = table[right];
            table[right] = temp;
            left++;
            right--;
        } 
    } // while left < right

    if (start < right)
        qsort(table,start,right);
    if (left < finish)
        qsort(table,left,finish);
}

Answer 1

1) Your function prototype doesn’t match the function declaration.

void qsort(TaxRecord table,int start,int finish);
void qsort(TaxRecord table[],int start,int finish)

2) You call the function with what appears to be a single array element instead of the array itself.

qsort(theEmployees[i],0,i);

3) You attempt to assign an array to a single TaxRecord variable.

TaxRecord temp = table;

4) You attempt to use an int temporary while swapping TaxRecord elements.

int temp = table[left];
table[left] = table[right];
table[right] = temp;

5) The error message sounds like there isn’t a defined operator< for your TaxRecord type.

My suggestion: instead of fixing your code just use the library qsort or std::sort, depending on whether this is C or C++.