赛格。逐行读取故障

Question

我正在尝试计算每行出现最多的众数或整数。

我得到一个打印两个值，然后是分段错误。

        for (i = 0; i < count; i++) {

            if (array[i]) {
                int i, j, k, cnt = 1, p, big;
                int b[MAX_NUM] = {0};
                printf("count:%d\n", count);
                for (i = 1; i <= array[i]; i++) {
                    for (j = i + 1; j <= array[i]; j++) {
                        if (array[i] == array[j])
                            printf("cnt:%d\n", cnt);
                        cnt++;
                    }
                    printf("cnt2:%d\n", cnt);
                    b[k] = cnt;
                    k++;
                    cnt = 1;
                }        
                big = b[k];
                p = 1;

                for (i = 2; i <= array[i]; i++) {
                    if (big < b[i]) {
                        big = b[i];
                        p = i;
                    }
                }
                printf("The element that occurs offen is %d\n", array[p]);
                printf("And it has occurred %d times\n", b[p]);
            }
        }
    }
}
}

return 0;
}

编辑：

在我的代码中查看这里的外观。打印的值是文件每一行上的数字，后跟一个空行，如下所示：

1
2
3
4
5
6
5
4
5

14
62
48
14
1
3
5
7
9

123
456
789
1234
5678

34
34
34
34
34

1

1
2
2
2
2
2
3
3
4
4
4
4
5
5
6
7
7
7
1
1

Integers: 9
.....

Answer 1

您在它们隐藏当前定义的内部范围内重新定义 i 和 p。这显然是无意的，因为 for 表达式看起来很错误：

if (array[i]) {
    int i, j, k=1, cnt = 1, p, big;
    //  ^
    //  Redefinition of i.
    //  You should use a different name for the loop index below
    //  Same remark for p, it is safer to not redefine local variables
    //  in inner scopes.  Any { starting a block creates a new scope
    //  in which variables can be defined, or in this case redefined.
     ...
    for (i = 1; i <= array[i]; i++) {
        ...
    for (i = 2; i <= array[i]; i++) {
        ...

在代码的同一区域，您使用k 而不事先初始化。

计算最大出现次数的代码可以放在一个单独的函数中并以这种方式简化：

#include <stdio.h>

// get the number of ocurrences of val in array a of size n
int get_number_of_occurrences(int a[], int n, int val) {
    int cnt = 0, i;

    for (i = 0; i < n; i++) {
        if (a[i] == val)
            cnt++;
    }
    return cnt;
}

// return the index for the number that occurs the most
int get_max_occurrence_index(int a[], int n) {
    int p = 0, cnt, max = 0, i;

    for (i = 0; i < n; i++) {
        cnt = get_number_of_occurrences(a, n, a[i]);
        if (max < cnt) {
            max = cnt;
            p = i;
         }
     }
     return p;
}

int main() {
    int i, n, a[20], max;

    printf("Enter the maximum number of elements\n");
    scanf("%d", &n);
    printf("Enter the elements\n");
    for (i = 0; i < n; i++) {
        scanf("%d", &a[i]);
    }
    i = get_max_occurrence_index(a, n);
    max = get_number_of_occurrences(a, n, a[i]);
    printf("The element that occurs most oftenly is %d\n", a[i]);
    printf("And it has occurred %d times\n", max);
    return 0;
}

如果你想在你的原始程序中使用这个逻辑，你应该在你读取文件的每一行使用它，而不是在它只适用于最后一行的末尾。行解析代码也不正确：您将第一个数字的ASCII值作为值，而不是用strtol()解析它。

这是一个更正的版本：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>

#define MAX_NUM 1000
#define MAX_LINE_LEN 2048
#define N 100

void fatal(const char *msg) {
    printf("%s\n", msg);
    exit(1);
}

int main(int argc, char *argv[]) {
    FILE *fp;
    char filename[100];
    char line[MAX_LINE_LEN];
    char *p;
    int array[MAX_NUM];
    int index, count, max;

    printf("Please enter the file name: \n");

    if (scanf("%99s", filename) != 1) {        
        fatal("Error in entering file.");
    }

    if ((fp = fopen(filename, "r")) == NULL) {
        fatal("Unable to open the file.");
    }

    while ((p = fgets(line, MAX_LINE_LEN, fp)) != NULL) {
        /* skip white space */
        p += strspn(p, " \t\n");
        if (*p == '#' || *p == '\0') {
            /* ignore comment and blank lines */
            continue;
        }
        /* scan and convert the numbers */
        for (count = 0; *p != '\0'; ) {
            if (isdigit((unsigned char)*p)) {
                array[count++] = strtol(p, &p, 10);
                printf("%d\n", array[count]);
            } else {
                /* skip to next space or end of string */
                p += strcspn(p, " \t\n");
            }
            /* skip white space after the number */
            p += strspn(p, " \t\n");
        }

        index = get_max_occurrence_index(array, count);
        max = get_number_of_occurrences(array, count, array[index]);

        printf("The element that occurs most often is %d\n", array[index]);
        printf("And it has occurred %d times\n", max);
    }
    fclose(fp);
    return 0;
}

Answer 2

也许我只是看不透你的代码，但我从来没有看到你将文件中的实际数字加载到任何变量或数组中。

您正在加载带有while ((p = fgets(line, MAX_LINE_LEN, fp)) != NULL) { 的行 在该循环中，您将此行分解为标记以计算您有多少个数字。

据我所知，array[count]++; 用于计算每行中有多少个数字。使用索引作为行号。

您应该首先考虑如何将数据转换为可用格式
您可以开始尝试将值加载到二维数组中。
使用第一个维度作为行号，第二个维度作为值。

如果你对自己的代码理解不够透彻，应该从更多的 cmets 入手
你用你的定义和变量做什么。
#define MAX_NUM 1000 //maximum number of lines

int array[MAX_NUM] = {0}; //index refers to line number of file. used to count numbers in each line.

// read file line by line, split every line into tokens to count amount of numbers
while ((p = fgets(line, MAX_LINE_LEN, fp)) != NULL) {
    if (count >= MAX_NUM) {
        fatal("Array error");
    }
    if (line[0] != '#') {
        p = strtok(line, " ");
        while (p != NULL) {
            if (isdigit(*p)) {
                array[count]++;
            }
            p = strtok(NULL, " ");
        }
    }
    count++;
    //printf("COUNT:%D\n", count);
}  

另外选择好的变量名会更好
#define MAX_NUM 1000 -> #define MAX_LINE_NUM 1000

我不知道你的变量 int i, j, k, cnt = 1, p, big; 做了什么。 给他们更好的名字或评论他们。不仅会帮助您，还会帮助您的助手，他们需要了解您打算对他们做什么。

首先我认为您需要有关该模式算法的帮助，所以我先写了这个：
使用非常基本的东西使其尽可能简单。 如果您知道如何将其放入函数中会更干净。 没有使用函数，因为您似乎完全不知道如何使用它们（您应该研究一下）

该算法正在执行以下操作：

1. 取数组中的第一个数字
2. 遍历数组，每次找到该数字时，都会增加一个counter
3. 将号码和计数保存为highest 和highestCnt
4. 对数组中的每个数字重复并覆盖highest 和highestCnt 每当count > highestCnt

当有多个出现次数最多的数字时，它只会记住最先计数的数字。如果要返回出现次数最多的所有数字，则需要更改 coude。 可以做一些事情，比如检查count == highestCnt，然后设置一些东西，这样你就知道没有最高计数的单个数字，直到你找到一个计数更高的数字。

#include<stdio.h>

#define sizea 100

int main(void) {
    int array[sizea] = { 1,3,6,8,3,6,7,4,6,9,0,3,5,12,65,3,76,5,3,54,
                         1,3,6,89,3,6,7,4,6,9,0,4,5,12,65,3,76,5,3,54,
                         1,9,6,8,3,45,7,4,6,9,0,89,5,12,65,3,76,5,3,54,
                         6,3,6,8,3,6,7,4,6,9,0,23,5,12,65,3,76,5,3,54,
                         1,3,6,90,3,6,7,4,6,9,0,5,5,12,65,3,76,5,3,54 };

    int number;
    int count = 1;
    int highest = 1;
    int highestCnt = 1;
    int end = sizea - 1;  //end defines at what element in the array the loop will end
    int j;  //j is used to load a number that will be count
    int i;  //i is used run through the array and compare every number the the one that is being count

    for (j = 0; j <= end; j++) {
        number = array[j];  // load a number to count
        count = 1; // start counting at 1

        for (i = j+1; i <= end; i++) {
            // if we find the same number again, we increase the counter
            // then we load the last element into the current array position 
            // then we change decrement "end" by 1
            // this is like throwing out all the numbers we allready count
            // using while instead of if so it will check the last element that was moved to current position as well
            // check for i <= end so it doesnt count twice when the last element equals our number
            while (array[i] == number && i <= end) {
                count++;
                array[i] = array[end];
                end--;
            }
        }
        // if the count of the number is highers the the previus highest, it's obviously our new highest count.
        if (count > highestCnt) {
            highest = number;
            highestCnt = count;
        }

    }
    printf("number: %i, count: %i", highest, highestCnt);
}