PHP Tutorial: Determine Zodiac Sign from Birthdate

The article presents a PHP program that determines a student's zodiac sign based on their birthdate, covering requirement analysis, design thinking, necessary PHP knowledge, implementation code, and result display.

Requirement analysis : The zodiac is matched to the month‑day range of the birthdate (e.g., March 21 – April 19 corresponds to Aries).

Design thinking : Two challenges are addressed – ensuring that a day value less than 10 is padded with a leading zero to avoid comparison errors, and implementing the zodiac‑judgment logic.

Knowledge base : The article reviews PHP conditional statements, including if , ternary ?: , if...else , if...elseif...else , and switch , providing their syntax.

Code implementation :

1. Define variables to store student information:

$name = '王六'; // save student name
$birth = '2003-08-07'; // save student birthdate

2. Split the birthdate string to obtain year, month, and day:

$temp = explode('-', $birth);
$stu_by = $temp[0];
$stu_bm = $temp[1];
$stu_bd = $temp[2];

3. Get the current year, month, and day (not strictly required for zodiac but shown as example):

$cur_y = date('Y'); // full year
$cur_m = date('n'); // month without leading zero
$cur_d = date('j'); // day without leading zero

4. Pad single‑digit day values with a leading zero:

if ($stu_bd < 10) {
  $stu_bd = '0' . $stu_bd;
}

5. Combine month and day into a comparable string:

$date = "$stu_bm.$stu_bd";

6. Determine the zodiac sign using a chain of if…elseif statements (the same logic could be expressed with switch ):

if ($date >= 1.21 && $date <= 2.19) {
  $const = '水瓶座';
} elseif ($date >= 2.20 && $date <= 3.20) {
  $const = '双鱼座';
} elseif ($date >= 3.21 && $date <= 4.20) {
  $const = '白羊座';
} elseif ($date >= 4.21 && $date <= 5.21) {
  $const = '金牛座';
} elseif ($date >= 5.22 && $date <= 6.21) {
  $const = '双子座';
} elseif ($date >= 6.22 && $date <= 7.22) {
  $const = '巨蟹座';
} elseif ($date >= 7.23 && $date <= 8.23) {
  $const = '狮子座';
} elseif ($date >= 8.24 && $date <= 9.23) {
  $const = '处女座';
} elseif ($date >= 9.24 && $date <= 10.23) {
  $const = '天秤座';
} elseif ($date >= 10.24 && $date <= 11.22) {
  $const = '天蝎座';
} elseif ($date >= 11.23 && $date <= 12.21) {
  $const = '射手座';
} else {
  $const = '魔羯座';
}

Result display : The computed zodiac constant is output, and an example screenshot of the result is shown in the original article.