PHP开发：按15递增计数（上限45）及用for循环计算军事时间间隔数

Hey there! Let's break down your two PHP problems step by step with practical, easy-to-follow code examples.

Requirement 1: Count Up by 15, Max Value 45 #

This is super straightforward with a for loop. We just set our starting value, increment by 15 each iteration, and stop when we hit 45. Adjust the starting number if you don't want to begin at 0:

// Start at 0, count up to 45 in 15-increment steps
for ($count = 0; $count <= 45; $count += 15) {
    echo $count . " "; // Output: 0 15 30 45
}

// If you want to start at 15 instead:
// for ($count = 15; $count <= 45; $count += 15) {
//     echo $count . " "; // Output: 15 30 45
// }

The loop works by initializing $count to your starting number, checking if it’s still ≤ 45, running the code inside, then adding 15 to $count each time until the condition fails.

Requirement 2: Calculate 15-Minute Blocks Between Military Times Using a For Loop #

First, we need to convert those 4-digit military time strings (like "0930") into total minutes since midnight—this makes math and looping way simpler. Then we can use a for loop to iterate through each 15-minute interval and count the blocks.

Step 1: Helper Function to Convert Military Time to Minutes #

Let’s write a quick function to turn a military time string into minutes:

function militaryToMinutes($time) {
    // Split the 4-digit string into hours and minutes
    $hours = (int)substr($time, 0, 2);
    $minutes = (int)substr($time, 2, 2);
    return $hours * 60 + $minutes;
}

Step 2: Use a For Loop to Count Blocks #

Now we can take our start and end times, convert them, then loop through each 15-minute slot:

$startTime = "0900";
$endTime = "1115";

$startMins = militaryToMinutes($startTime);
$endMins = militaryToMinutes($endTime);

$blockCount = 0;

// Loop from start time to end time, incrementing by 15 minutes each time
for ($currentMins = $startMins; $currentMins < $endMins; $currentMins += 15) {
    $blockCount++;
}

echo "Total 15-minute blocks: " . $blockCount; // Output: 9 for 0900→1115

Quick Note on Your Example:

You mentioned 0900 to 1115 should be 8 blocks, but mathematically that’s 2 hours and 15 minutes (135 minutes), which divides into 9×15-minute slots. The code above correctly returns 9 here. Your second example (1130→1430) will return 12 blocks, which matches your expectation—perfect!

Edge Cases to Handle: #

• If $startTime equals $endTime, the loop won’t run, so $blockCount stays 0 (correct, since there are no blocks between the same time).
• If you might pass an end time earlier than the start time, add a quick swap check:

  if ($startMins > $endMins) {
      [$startMins, $endMins] = [$endMins, $startMins];
  }
  

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