不能重新声明函数做while循环

Question

I'm new to functions and I'm probably not doing it as well as I could so could use some help with this. I'm pulling stock information from a web sites API. All the information being pulled is done with several .php pages and I have one file that includes all the necessary pages. So I have something like this: pullBalanceSheet.php for all the balance sheet data pullIncomeStatement.php for all the income sheet data etc, there are 10 pages. All pages can run independently of each other and was created like this to make easy to test each API call. I have a master page (pullData.php) that contains the necessary includes for each page so it effectively runs all the pages as a single page. I hope this makes sense.

Some of my pages contain a function and this is where I'm probably not doing it the best way, but the pages work to pull the correct data. These pages pull quarterly financial information for the last 5 years. The issue is that every company states quarterly financial dates differently. So let's say it's January 2019 and some company quarterly will state Quarter 2, 2019 even though it really isn't Quarter 2 2019 until March 2019. So my code basically needs to capture possible future dates, so my code looks like this:

    $fiscal_year = date("Y");
    $fiscalPeriod = 'Q1';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);
    $fiscalPeriod = 'Q2';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);
    $fiscalPeriod = 'Q3';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);
    $fiscalPeriod = 'Q4';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);
    //year 2
    $fiscal_year = $fiscal_year-1;
    $fiscalPeriod = 'Q1';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);
    $fiscalPeriod = 'Q2';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);
    $fiscalPeriod = 'Q3';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);
    $fiscalPeriod = 'Q4';
      pulldataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey);

..etc for 5 years. The API looks at the $fiscal_year and the $fiscal_period and returns data if it's available.

The function is this:

    function pullDataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey) {
      // function code here
    }

All my code works when pulling one stock. I'm now working on pulling multiple stocks by using a while loop on my pullData.php master page and this is where I'm having the issue. Since the code is repeating itself for each new stock, I'm getting a fatal error cannot redeclare function. I understand why this is happening since the loop is being treated as a single page and when it hits the second stock, it errors. I'm trying to figure out how to get around this. I have used

    if(!function_exists('pullDataBS')) { 
      function pullDataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey) {
      //function code here
    }
    }       

And I get a undefined function pulldataBS error when it hits the function call at the very first time (3rd line of code where it tries the first pulldataBS in this example). Here is my pulldata.php master page:

    while($research = mysqli_fetch_array($queryResearch)) {  
      $_SESSION['ticker']  = $research['symbol']; 
      include('pullBalanceSheet.php'); 
      include('pullIncomeStatement.php');
      // etc
    }

I'm assuming the !function_exists is not correct or I have some other critical issue with the way I coded my function. I hope this all makes sense. Let me know if you need any other code. Thanks in advance!!

Answer 1

First of all, you should not include pullBalanceSheet.php and pullIncomeStatement.php files in each iteration of while loop. Take below two lines outside of while loop.

include('pullBalanceSheet.php'); 
include('pullIncomeStatement.php');

Now comes to the problem, you must not declare your function(s) over and over again, just declare it once and call it (with appropriate arguments) multiple times as per your need. Having said that, you can use defined() along with define() functions to solve your function redelaration problem.

if(!defined('PULL_DATA_BS')){
    define('PULL_DATA_BS', 'pullDataBS');

    function pullDataBS($fiscal_year,$fiscalPeriod, $username,$password,$apiKey) {
        //function code here
    }
}

This way this function won't get declared more than once. Ideally, you are supposed to encapsulate the entire code of a file with below block.

xyz.php

<?php
    if(!defined('XYZ_PHP')){
        define('XYZ_PHP', 'xyz.php');

        // file code

    }
?>

This way, you will prevent yourself(and somebody else) from including this file code more than once.