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[PHP] Basic arithmetic help


donatastommy
Go to solution Solved by donatastommy,

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My task:

 

You currently have $20000 in your bank account.

You are to count the number of perfect squares from 1 to your amount. 

 

So first of all, I am trying to print out all the perfect squares (1,4,9,16, etc). That's what I want to do first, and I'm having trouble with it.

My code:

 

<?php
$x=0;
while($x<=20000)
{
$sqrt = sqrt($x);
if($x == $sqrt * $sqrt)
{echo $x . "</br>";}
$x++;
}
?>

 

But all it does is print this, all the way to 1999:

 

 

 

0
1
4
9
11
14
16
17
21
22
25
27
30
33
34
35
36
39
41
42
44
46
47
49
53
54
55
56
57
62
64
67
68
69
70
71
74
79
81
83
84
85
86
88
90
91
93
98
99
100
101
103
108
110
114
118
120
121
126
129
130

 

 

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This is quite simple, you should look at pow to complete this. See the following:

<?PHP

  //### Start at 1
  $currentNumber = 1;
 
  //### While true, continuos till break is hit
  while(true) {   
    
    //### Multiply the number by itself
    $number = pow($currentNumber, 2);
    
    //### If the number is less than 20000 display it
    //### If the number is greater than 20000, break the while loop
    if($number < 20000) {
      echo $number .'<br>';
    } else {
      break;
    }
    
    //### Add 1 to the current number
    $currentNumber++;
  }

?>
Edited by PaulRyan
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This is quite simple, you should look at pow to complete this. See the following:

<?PHP

  //### Start at 1
  $currentNumber = 1;
 
  //### While true, continuos till break is hit
  while(true) {   
    
    //### Multiply the number by itself
    $number = pow($currentNumber, 2);
    
    //### If the number is less than 20000 display it
    //### If the number is greater than 20000, break the while loop
    if($number < 20000) {
      echo $number .'<br>';
    } else {
      break;
    }
    
    //### Add 1 to the current number
    $currentNumber++;
  }

?>

 

I'll test this when I get home. I believe it should work, however, how would you do this without pow or gdb?

Basically you're if condition is incorrect. What you wrote would technically be always true, and should echo out every number. The reason it doesn't is due to computer limitations when it comes to floating point values (rounding errors).

 Yeah, realized that when I was eating lunch lol

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