This is a simple question,I guess, but I couldn't figure it out.
How do I get a total sum of sequential numbers in PHP Like 2,4,6,8,10 . . . .1000
Thank you for the help.
$sum = array_sum(explode(',', '2,4,6,8'));
edit: if you just want the sum of even numbers within a range you could
$sum = array_sum(range(2,1000,2));
Split on , and then sum:
$numbers = explode(",", $string);
$total = array_sum($numbers);
echo $total;
Note that this requires only numbers and , any other characters will be subject of being typecasted to an integer (which could result in unexpected results).
If you wanted to you could also use the Arithmetic progression sum and just do
$total = ($firstNumber + $lastNumber) * $count / 2
This will work as long as the numbers are a expressable in the format
an = a1 + (n - 1)d
Your sequence could be described as
an = 2 + (n - 1)2
So we can apply the Arithmetic progression sum and get
(2 + 1000) * 500 / 2 = 250,500
This will be much much faster than any array_sum method of calculating it.
Related
How to extract the percentage from the array
The result is as follows: 41 - 16 - 8 - 33
Total is 98, not 100
How to make it = 100
$sum = array(500.36,200.32,100.09,400);
$total = array_sum($sum);
foreach($sum as $val){
$st = intval($val / $total * 100 );
echo $st.'<br>';
}
The reason is: precision :)
With intval() you skip the decimals. so 41+16+8+33 is REALLY 98.
If you add them with 2 decimals:
41.66 + 16.68 + 8.33 + 33.31 = 99.98
If you do round() instead of intval() you'll round the values so it'll be more close statistically. you'll get: 42 + 17 + 8 + 33 = 100
BUT! if you want to make sure the sum is 100, than you should pick one number (I suggest the biggest one) to calculate that as: 100 - sum(the rest).
Rounding!
Take the number 500.36;
500.36 / 1200.77 * 100:
41,669928463
Since you're using intval those deciamals are lost, remove intval to keep the decimals, then you'll reach 100 total.
Consider an extra variable to check this;
<?php
$sum = array(500.36,200.32,100.09,400);
$total = array_sum($sum);
$test = 0;
foreach($sum as $val){
$st = $val / $total * 100;
echo $st.'<br>';
$test += $st;
}
echo $test;
41.66992846257
16.682628646618
8.3354847306312
33.311958160181
100
Try it online!
you are using intval(). you should use round() with the precision of 2. you are skipping fractions by converting answer to integer. PHP is using floor method so your answer is losing fractions. here is the code
$sum = array(500.36,200.32,100.09,400);
$total = array_sum($sum);
foreach($sum as $val){
$st = round($val / $total * 100, 2 );
echo $st.'<br>';
}
If you make an intval to the result you cut the last values.
Without intval you can see the problem.
41.66992846257
16.682628646618
8.3354847306312
33.311958160181
So work with that numbers or round it on 2 decimal numbers.
$st = number_format($val / $total * 100, 2, '.', '');
something like this.
I need to find the first and last number with length n and starting with digit d.
For example.
i need to find the first and last number with length 6 and starting in 2
The result should be first number=200000 and last number=299999 .
I there any functions available in php to help me to get a logic to solve this.??
Hope Someone can help me..
You could try relying on the fact that the smallest number will end in all 0's and the largest in all 9's, and then use str_repeat to generate the appropriate tailing digits:
echo $d . str_repeat('0', $n-1);
echo $d . str_repeat('9', $n-1);
For $d = 2 and $n = 6, this will give you 200000 and 299999.
If you need them as integers, just do
$start = (int)($d . str_repeat('0', $n-1));
$finish = (int)($d . str_repeat('9', $n-1));
var_dump($start);
var_dump($finish);
Output:
int(200000)
int(299999)
Here is an option which uses algebra to get the numbers you want. Based on the width of the number, we can compute the smallest number with that width. Then, the starting number is simply this value times the starting first digit. And the ending number can also be teased out.
$length = 6;
$first = 2;
$begin = pow(10, $length-1);
$start = $first * $begin;
$end = (($first + 1) * $begin) - 1;
echo $start . "\n";
echo $end;
200000
299999
Demo
This should outperform the accepted answer because generating the numbers requires only a few arithmetic operations, rather than complex string manipulation operations.
In PHP, I need to round off a number to the next whole number. For example, in my program, I am using the round as below.
$val = round(count($names)/15);
If count($names) is 1.2, I need it to be rounded off to 2 instead of 1. I tried to do the below approach.
$val = round(count($names)/15) + 1;
However, in the above approach, if I have count($names) as 1.6, It is getting rounded off to 3 as I increment it by 1.
Is there a way where no matter what the decimal value is, it needs to be rounded off to the next whole number?
How about using ceil()
http://php.net/manual/en/function.ceil.php
Then your code becomes:
$val = ceil(count($names)/15);
Try This:
$val = round(count($names)/15, PHP_ROUND_HALF_DOWN) + 1;
What would be a good way to generate 7 unique random numbers between 1 and 10.
I can't have any duplicates.
I could write a chunk of PHP to do this (using rand() and pushing used numbers onto an array) but there must be a quick way to do it.
any advice would be great.
Create an array from 1 to 10 (range).
Put it in random order
(shuffle).
Select 7 items from the array (array_slice)
Populate an array with ten elements (the numbers one through ten), shuffle the array, and remove the first (or last) three elements.
Simple one-liner:
print_r(array_rand(array_fill(1, 10, true), 7));
Check out the comments in the php manual, there are several solutions for this.
An easy one is this one:
$min = 1;
$max = 10;
$total = 7;
$rand = array();
while (count($rand) < $total ) {
$r = mt_rand($min,$max);
if (!in_array($r,$rand)) $rand[] = $r;
}
Whole numbers? Well, if you want 7 out of 10 then you more efficiently DON'T want 3 out of 10.
Feel free to use any of the other responses but instead of creating 7 numbers start with 10 and eliminate 3. That will tend to speed things up by more than double.
The "shuffle" method has a MAJOR FALW. When the numbers are big, shuffle 3 billion indexs will instantly CAUSE 500 error. Here comes a best solution for really big numbers.
function getRandomNumbers($min, $max, $total) {
$temp_arr = array();
while(sizeof($temp_arr) < $total) $temp_arr[rand($min, $max)] = true;
return $temp_arr;
}
Say I want to get 10 unique random numbers from 1 billion to 4 billion.
$random_numbers = getRandomNumbers(1000000000,4000000000,10);
PS: Execution time: 0.027 microseconds
I have a part in my code where I need to divide and have a remainder instead of a decimal answer.
How can I do this?
$quotient = intval($dividend / $divisor);
$remainder = $dividend % $divisor;
Using intval instead of floor will round the quotient towards zero, providing accurate results when the dividend is negative.
You can do what you are describing using the "%" (modulus) operator. The following code is an example of dividing with a remainder.
$remainder=$num % $divideby;
$number=explode('.',($num / $divideby));
$answer=$number[0];
echo $answer.' remainder '.$remainder;
A solution for positive and negative numbers:
$quotient = $dividend / $divison;
$integer = (int) ($quotient < 0 ? ceil($quotient) : floor($quotient));
$remainder = $dividend % $divisor;
The mathematical correct answer is:
remainder = dividend % divisor;
quotient = (dividend - remainder) / divisor;
and the remainder verifies the condition 0 <= remainder < abs(divisor).
Unfortunately, many programming languages (including PHP) don't handle the negative numbers correctly from the mathematical point of view. They use different rules to compute the value and the sign of the remainder. The code above does not produce the correct results in PHP.
If you need to work with negative numbers and get the mathematical correct results using PHP then you can use the following formulae:
$remainder = (($dividend % $divider) + abs($divider)) % abs($divider);
$quotient = ($dividend - $remainder) / $divider;
They rely on the way PHP computes modulus with negative operands and they may not provide the correct result if they are ported to a different language.
Here is a script that implements these formulae and checks the results against the values provided as example in the aforementioned mathematical correct answer.
If you need to look it up, the % operator is called mod (or modulus).
I had to develop this approach because my numerator was a float value and modulus was rounding results.
Using Raffaello's approach offered here for dividing floats and taking from Sam152's solution above came up with the following.
$a = 2.1;
$b = 8;
$fraction = $a / (float) $b;
$parts = explode('.', $fraction);
$int = $parts[0];
$remainder = $score - ($int*$b) ;
Use This Function Its an array
Description
array gmp_div_qr ( resource $n , resource $d [, int $round ] )
The function divides n by d .
reference : http://php.net/manual/en/function.gmp-div-qr.php
An example to show strings like 1 hour 6 minutes using floor() and modulus (%) if only minutes/seconds given:
$minutes=126;
if($minutes < 60) {
$span= $minutes.' min.';
} else {
$rem=$minutes % 60;
$span=floor($minutes/60).' h. '. (($rem>0) ? $rem.' min.':'');
}
// echo 'Hello Jon Doe, we notify you that even will last for 2 h. 6 min.
echo 'Hello Jon Doe, we notify you that event will last for '.$span;
It seems to be an old post, but for those who might be interested here is a very light package that could meet your needs: https://github.com/romainnorberg/residue (feedbacks are welcome)