C 程序生成奇数输出

Question

最近开始尝试学习C，并决定做一些Euler挑战的项目。我写了这段代码来解决这个问题，但是当它运行时它输出的数字应该是不可能的。我已经尝试了一切来修复它。包括让我的一些整数变长，这些似乎都不起作用。任何输入都会很棒，谢谢!

#include <stdio.h>

int main(){
    char num[] = 
"73167176531330624919225119674426574742355349194934"
"96983520312774506326239578318016984801869478851843"
"85861560789112949495459501737958331952853208805511"
"12540698747158523863050715693290963295227443043557"
"66896648950445244523161731856403098711121722383113"
"62229893423380308135336276614282806444486645238749"
"30358907296290491560440772390713810515859307960866"
"70172427121883998797908792274921901699720888093776"
"65727333001053367881220235421809751254540594752243"
"52584907711670556013604839586446706324415722155397"
"53697817977846174064955149290862569321978468622482"
"83972241375657056057490261407972968652414535100474"
"82166370484403199890008895243450658541227588666881"
"16427171479924442928230863465674813919123162824586"
"17866458359124566529476545682848912883142607690042"
"24219022671055626321111109370544217506941658960408"
"07198403850962455444362981230987879927244284909188"
"84580156166097919133875499200524063689912560717606"
"05886116467109405077541002256983155200055935729725"
"71636269561882670428252483600823257530420752963450";

    int inc;
    long int next_biggest = 0;
    for (inc = 0; inc <= 986; inc++){
        int temp;
        long int total = (int)num[inc];
        for (temp = 1; temp <= 13; temp++){
            total *= (int)num[(inc + temp)];
        }
        if ((total > next_biggest)){
            next_biggest = total;
            printf("Next Biggest Number: %ld\n", total);
        }
    }
}

Answer 1

线

long int total = (int)num[inc];

看起来它将 '3' 转换为 int 3，但实际上并没有。它所做的是获取 '3' 的 ASCII 值并将其分配给您的 int。

修复它，你的程序就会运行良好:)

long int total = num[inc] - '0';

基本上这里发生的事情是我们得到一个 char 值(这是一个数字)并得到它的 ASCII 码。然后，基于在 ASCII 中所有数字都在一个以“0”开头的连续值 block 中这一事实，我们计算这些数字的面值并将其用作 int。

纠正上面的行后，这是程序的输出:

Next Biggest Number: 2032807552
Next Biggest Number: 2084481664
Next Biggest Number: 2141716480
Next Biggest Number: 2144206848