Project Euler 8 - Redux

Spurred by this question: Project Euler #8 I decided to try to solve it with as clean code as possible.

Here is the problem formulation:


The four adjacent digits in the 1000-digit number that have the
greatest product are 9 × 9 × 8 × 9 = 5832.


73167176531330624919225119674426574742355349194934
96983520312774506326239578318016984801869478851843
85861560789112949495459501737958331952853208805511
12540698747158523863050715693290963295227443043557
66896648950445244523161731856403098711121722383113
62229893423380308135336276614282806444486645238749
30358907296290491560440772390713810515859307960866
70172427121883998797908792274921901699720888093776
65727333001053367881220235421809751254540594752243
52584907711670556013604839586446706324415722155397
53697817977846174064955149290862569321978468622482
83972241375657056057490261407972968652414535100474
82166370484403199890008895243450658541227588666881
16427171479924442928230863465674813919123162824586
17866458359124566529476545682848912883142607690042
24219022671055626321111109370544217506941658960408
07198403850962455444362981230987879927244284909188
84580156166097919133875499200524063689912560717606
05886116467109405077541002256983155200055935729725
71636269561882670428252483600823257530420752963450


Find the thirteen adjacent digits in the 1000-digit number that have
the greatest product. What is the value of this product?

This is my implementation:

```
#include
#include
#include
#include

static const char* c_input =
"73167176531330624919225119674426574742355349194934"
"96983520312774506326239578318016984801869478851843"
"85861560789112949495459501737958331952853208805511"
"12540698747158523863050715693290963295227443043557"
"66896648950445244523161731856403098711121722383113"
"62229893423380308135336276614282806444486645238749"
"30358907296290491560440772390713810515859307960866"
"70172427121883998797908792274921901699720888093776"
"6572733300

It is good the way you do not use using namespace std;. This practice will save you a lot of headaches later on.

In fact, the only problem I found with this code is that you do not use braces around one-line if statements.

if (next_zero == std::string::npos)
    next_zero = input.size();

Using braces will not change the runtime behavior of your code, but it can help you prevent errors if you make a mistake, like Apple did with their Apple SSL bug.

StackExchange Code Review Q#83372, answer score: 3