求开发基于距离的动态计价函数，附计价规则与现有PHP代码

First, let's clear up a small overlap in your original pricing rules (I’m assuming this was a typo to avoid conflicting tiers):

• 0-10km: ₹10/km
• 10-15km: ₹10/km
• 15-20km: ₹9/km
• 20-25km: ₹8.5/km
• 25-30km: ₹8/km
• 30-40km: ₹7.5/km
• 40km+ (including 50km and beyond): ₹7/km

Your current code has two critical issues blocking correct pricing:

1. The $km variable includes a 'km' string suffix, so you can’t multiply it directly for calculations.
2. The pricing logic only uses a flat rate of 10 or 9, which doesn’t align with your tiered rules.

Here’s the optimized code with proper tiered pricing, plus better maintainability for future admin updates:

// Reusable function to calculate tiered ride price
function calculateRidePrice(float $distance): float {
    // Define pricing tiers (easy to edit for admins later)
    $pricingTiers = [
        ['min_km' => 0, 'max_km' => 10, 'rate' => 10.0],
        ['min_km' => 10, 'max_km' => 15, 'rate' => 10.0],
        ['min_km' => 15, 'max_km' => 20, 'rate' => 9.0],
        ['min_km' => 20, 'max_km' => 25, 'rate' => 8.5],
        ['min_km' => 25, 'max_km' => 30, 'rate' => 8.0],
        ['min_km' => 30, 'max_km' => 40, 'rate' => 7.5],
        ['min_km' => 40, 'max_km' => PHP_INT_MAX, 'rate' => 7.0] // Covers all distances over 40km
    ];

    $totalPrice = 0.0;
    $remainingDistance = $distance;

    foreach ($pricingTiers as $tier) {
        if ($remainingDistance <= 0) break;

        // Calculate how much of the remaining distance falls into this tier
        $tierDistance = min($remainingDistance, $tier['max_km'] - $tier['min_km']);
        // Only charge if the distance is within the tier's range
        if ($distance > $tier['min_km']) {
            $totalPrice += $tierDistance * $tier['rate'];
            $remainingDistance -= $tierDistance;
        }
    }

    return $totalPrice;
}

foreach ($usersInfo as $index => $users) {
    $ridefrom = $users['ride_from'];
    $rideto = $users['ride_to'];
    
    // Parse latitude/longitude coordinates
    $tempLatLong = explode(',', $ridefrom);
    $tempLatLong1 = explode(',', $rideto);
    $key = ['lat', 'long'];
    $to = array_combine($key, $tempLatLong);
    $from = array_combine($key, $tempLatLong1);
    
    // Calculate distance and extract numeric value (remove 'km' suffix)
    $distanceStr = distanceCalculation($from['lat'], $from['long'], $to['lat'], $to['long']);
    $km = (float) str_replace('km', '', trim($distanceStr)); // Convert to pure number for calculations
    $usersInfo[$index]['distance'] = $km . 'km'; // Store with unit for display
    
    // Calculate tiered price
    $price = calculateRidePrice($km);
    // Optional: Format price to 2 decimal places for currency
    $usersInfo[$index]['price'] = number_format($price, 2);
}

return $usersInfo;

Key Improvements: #

• Fixed Distance Handling: We extract the numeric value of the distance first, so arithmetic operations work correctly.
• Encapsulated Pricing Logic: The calculateRidePrice() function keeps tiered rules separate from the main loop, making it easy to update rates or add new tiers later.
• Accurate Tier Calculation: The function splits the ride distance into each tier, ensuring you charge the correct rate for every segment of the journey.
• Maintainability: Admins can edit the $pricingTiers array directly (or you can move it to a config file/database) without rewriting core code.

Optional Enhancements: #

• Store the $pricingTiers array in a database or config file so admins can edit rates via a backend UI.
• Add validation for invalid distance values (e.g., negative numbers) in the calculateRidePrice() function.
• Round the final price to the nearest whole number if needed for your currency setup.

内容的提问来源于stack exchange，提问作者new developer