tomhurst

I've kept my loop at the moment, is anyone able to explain what I'm doing wrong? The resulting number I'm getting is incorrect. <?php $string="7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"; $numberCount = strlen($string); $answer2=0; for($i=0; $i < $numberCount-14; $i++) { $answer1 = 1; for($j = $i; $j<=$i+13; $j++) { if (substr($string,$i,1)==0) { $i = $i+13; break; } else { $subString = substr($string,$j,1); $answer1 = $answer1 * $subString; } } if ($answer1 > $answer2) { $answer2 = $answer1; } } echo $answer2; ?>

Ah - Sorry - New to this still! I'm moved my if statement out of the inner loop - That does make more sense (I hope that's what you meant!) I'm not fully understanding your rolling product method. Is it incorrect to do this with two loops then? <?php $string="7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"; $numberCount = strlen($string); $answer2=0; for($i=0; $i < $numberCount-14; $i++) { $answer1 = 1; for($j = $i; $j<13; $j++) { $subString = substr($string,$j,1); $answer1 = $answer1 * $subString; } if ($answer1 > $answer2) { $answer2 = $answer1; } } echo $answer2;

Hey - I only started learning PHP a few days ago so forgive me. I've done Codecademy and SoloLearn which teach you the basics, and now looking to practise and learn more. I've had a go at some of the scenarios on Project Euler, and I'm stuck on scenario 8. In my head, it looks like my code should work. It's producing a number, but it's the incorrect answer apparently. Can anyone tell me where I'm going wrong? I hope I'm not completely off! This is the problem: https://projecteuler.net/problem=8 This is what I've written: <?php $string="7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450"; $number=7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450; $numberCount = strlen($string); $answer1 = 1; $answer2 = 0; $subString; for($i=0; $i < $numberCount-14; $i++) { $answer1 = 1; for($j = $i; $j<13; $j++) { $subString = substr($string,$j,1); $answer1 = $answer1 * $subString; if ($answer1 > $answer2) { $answer2 = $answer1; } } } echo $answer2;