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PHP Exercises: Find the customer number that has traded for the second consecutive for the second consecutive month from last month and the number of transactions

PHP: Exercise-70 with Solution

Record section of ABC company records the customer number and the trading date for each month. Write a PHP program to find the customer number that has traded for the second consecutive for the second consecutive month from last month and the number of transactions.
The data of this month and the data of last month are separated by a blank line of one line and given.
Transaction format:
c1 , d1
c2 , d2
...
...
ci (1 ≤ ci ≤ 1,000) is an integer represents the customer number, di (1 ≤ di ≤ 31) is an integer represents the trading date.

Sample Solution: -

PHP Code:

<?php
$x = array();
while (true) {
    $a = rtrim(fgets(STDIN));
    if ($a === '') {
        break;
    }
    list($n, $d) = explode(',', $a);
    if (!isset($x[$n])) {
        $x[$n] = 0;
    }
    $x[$n]++;
}
 
$y = array();
while (true) {
    $a = rtrim(fgets(STDIN));
    if ($a === '') {
        break;
    }
    list($n, $d) = explode(',', $a);
    if (!isset($x[$n])) {
        continue;
    }
    if (!isset($y[$n])) {
        $y[$n] = $x[$n];
    }
    $y[$n]++;
}
echo "Customer number and the number of transactions:\n";
ksort($y);
foreach ($y as $k => $v) {
    echo sprintf('%d %d', $k, $v) . PHP_EOL;
}

?>

Sample Input:
125,10
55,12
34,14

125,3
55,4
125,5

Sample Output:

Customer number and the number of transactions:
55 2
125 3

Flowchart:

Flowchart: Find the customer number that has traded for the second consecutive for the second consecutive month from last month and the number of transactions.

PHP Code Editor:

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PHP: Tips of the Day

Why shouldn't I use mysql_* functions in PHP?

The MySQL extension:

  • Is not under active development
  • Is officially deprecated as of PHP 5.5 (released June 2013).
  • Has been removed entirely as of PHP 7.0 (released December 2015)
  • This means that as of 31 Dec 2018 it does not exist in any supported version of PHP. If you are using a version of PHP which supports it, you are using a version which doesn't get security problems fixed.
  • Lacks an OO interface
  • Doesn't support:
    • Non-blocking, asynchronous queries
    • Prepared statements or parameterized queries
    • Stored procedures
    • Multiple Statements
    • Transactions
    • The "new" password authentication method (on by default in MySQL 5.6; required in 5.7)
    • Any of the new functionality in MySQL 5.1 or later

Since it is deprecated, using it makes your code less future proof.

Lack of support for prepared statements is particularly important as they provide a clearer, less error-prone method of escaping and quoting external data than manually escaping it with a separate function call.

Ref : https://bit.ly/2BIIsF0