pennineacute
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Thanks for that, very much appreciated.
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I am after some help for a project I am doing pls. I am writing a program to display the truth table of a boolean expression and so far all is good. I decided to convert the input into reverse polish notation, so I could get the expression into priority order. This works. The program displays the truth table inputs, with no problems, and I am now working on the Boolean part. If you entered for eg, a+b.c, I have stored the reverse polish notation in a array. In this would be stored a b c . + in elements 0 to 4 As each row input is calculated eg a b c output 0 0 0 I then want to display the output. My first idea was to read through the array until I hit a boolean operator and then perform this with the top two variables in my stack, in this case a.b but when trying values, I can get a boolean output for and, or and xor, but not for NOT, as can be see from the attachment My program is live at http://andylittlewood.co.uk The coding I was using to test the boolean output is echo "1 and 1 = "; echo 1 && 1; echo "<br>1 or 1 = "; echo 1 || 1; echo "<br> 1 xor 1 = "; echo true ^ true; echo "<br>Not 1 = ";echo !(true); I cannot put my full coding on here, as it is a project and do not want to plagiarise.
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Aprreciate that link, thanks
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Re your first comment. Let's say testing to see if 100 is prime. You only have to check up to 10 which is the square root EG, if 2 is a factor of 100, then so is 50 4 is a factor of 100, then so is 25 5 is a factor of 100, then so is 20 10 is a factor of 100, which is a repeated factor, as 100/10 = 10 That is why I only went up to the square root. re second. When I first wrote the program, I just wanted to see if a number was prime. Then I decided to enhance it, by showing the factors of a non-prime number. So using 100 as an example, after testing that division by 2 shows it is a non-prime number and therefore 2 and 50 are factors, I need to carry on testing, to get the remaining factors.
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Program is running here http://andylittlewood.co.uk
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I was writing a program to calculate whether a number was prime. It worked no issues and was quite fast. I then decided to enhance this, by calculating the factors of the number, if the number was not prime. This has dramatically slowed the program, for the following reason. Initialially I set is_it_prime to true, thereby assuming that the number was prime, until proven otherwise I then ran a while loop with two conditions, one being is_it_prime being true. Once a number has been proven not to be prime, it is a waste to carry on testing. Now to get my factors working, I have had to remove this boolean condition. Was wondering if anyone could come up with any other ideas. </head> <body> <body style="background-color:grey"> <?php $number_to_test=$_POST["number"]; $factors=array(); $factorposition=0; $interim_testing_number=2; $is_it_prime=true; // Assume number is prime unless proven not to be $max_loop = sqrt($number_to_test); while ($interim_testing_number<=$max_loop) { if ($number_to_test % $interim_testing_number==0 ){ $is_it_prime=false; // Number is definately not prime as no remainder $factors[$factorposition]=$interim_testing_number; $factorposition++; if ($number_to_test/$interim_testing_number != $interim_testing_number) { $factors[$factorposition]=$number_to_test/$interim_testing_number; $factorposition++; } } $interim_testing_number++; } if ($is_it_prime && $number_to_test>1) { print "$number_to_test is PRIME"; } else { print "$number_to_test is NOT PRIME<br>"; sort($factors); if ($number_to_test > 1){ print "Its factor(s) are "; if ($factorposition-1>0){ for ($i=0;$i<$factorposition-1;$i++){ echo "$factors[$i], "; } echo "and ".$factors[$factorposition-1]; } else { echo $factors[0]; } } else { echo "Numbers less than 2 are not prime by default"; } } print "<br><br><br>"; ?> <a href="index.html"><img src="Images/ilovemaths.png" height=200 witdth=170 alt="Maths is Fun"/></a> </body> </html>
