﻿ PHP Exercise: Print out the sum of pairs of numbers of a given sorted array of positive integers that is equal to a given number - w3resource # PHP Exercises: Print out the sum of pairs of numbers of a given sorted array of positive integers that is equal to a given number

## PHP: Exercise-44 with Solution

Write a PHP program to print out the sum of pairs of numbers of a given sorted array of positive integers which is equal to a given number.

Sample Solution: -

PHP Code:

``````<?php
function find_Pairs(\$nums, \$pair_sum) {
\$nums_pairs = "";
for (\$i = 0; \$i <= count(\$nums); \$i++) {
for (\$j = \$i + 1; \$j < count(\$nums); \$j++) {
if (\$nums[\$i] + \$nums[\$j] == (int)\$pair_sum) {
\$nums_pairs .= \$nums[\$i] . "," . \$nums[\$j] . ";";
}
}
}
return \$nums_pairs;
}
\$nums = array(0,1,2,3,4,5,6);
echo find_Pairs(\$nums, 7)."\n";
echo find_Pairs(\$nums, 5)."\n";
?>
```
```

Sample Output:

```1,6;2,5;3,4;
0,5;1,4;2,3;
```

Flowchart: PHP Code Editor:

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﻿

## PHP: Tips of the Day

Get first key in a (possibly) associative array?

Starting from PHP 7.3, there is a new built in function called array_key_first() which will retrieve the first key from the given array without resetting the internal pointer. Check out the documentation for more info.

You can use reset and key:

```reset(\$array);
\$first_key = key(\$array);
```

It's essentially the same as your initial code, but with a little less overhead, and it's more obvious what is happening.

Just remember to call reset, or you may get any of the keys in the array. You can also use end instead of reset to get the last key.

If you wanted the key to get the first value, reset actually returns it:

`\$first_value = reset(\$array);`

There is one special case to watch out for though (so check the length of the array first):

```\$arr1 = array(false);
\$arr2 = array();
var_dump(reset(\$arr1) === reset(\$arr2)); // bool(true)
```

Ref : https://bit.ly/32ecxHN