二维数组打印不正确

2D Array incorrectly printing

我在正确打印旅行商问题的二维数组时遇到问题。我正在使用输入重定向从文本文件中获取输入。该文件包含城市和弧线以及城市之间的距离。这是一个小例子。

c 1
c 2
a 1 2 1400

设置数组并绘制城市之间的距离后,我使用嵌套的 for 循环打印出数组,但它看起来像这样。

    0       1       2       3       4       5

    1       0       1400    1800    4000    3500

    2       1       0       0       3400    3600

    3       1800    1200    0       2300    0

    4       4000    3400    2300    0       2100

    5       3500    3600    0       2100    0

编辑:我想让它看起来像这样

    0       1       2       3       4       5

    1       0       1400    1800    4000    3500

    2       1400    0       1200    3400    3600

    3       1800    1200    0       2300    2700

    4       4000    3400    2300    0       2100

    5       3500    3600    2700    2100    0

我尝试以不同的方式操作 for 循环,但我似乎无法弄清楚我的问题出在循环中的什么地方,或者它是否在我的代码中的其他地方。

// Sets up the array
int CityArray [6][6] = { {0, 0, 0, 0, 0, 0},
                         {0, 0, 0, 0, 0, 0},
                         {0, 0, 0, 0, 0, 0},
                         {0, 0, 0, 0, 0, 0},
                         {0, 0, 0, 0, 0, 0},
                         {0, 0, 0, 0, 0, 0}
                       };

int main(void) // Takes in a variable number of arguments
{
    // Sets a string input for the city
    char Cbuffer[32];
    char *b = Cbuffer;
    size_t cbufsize = 32;
    size_t cinput;

    // Other vairables
    int x = 1; // used to go through the array
    int n1, n2, n3, n4, cost; // variables to store the value pulled the cost from the arc

    // Reads in the city and sets the prices for each arc
    while((cinput = getline(&b, &cbufsize, stdin)) != -1)
    {
        if (Cbuffer[0] == 'c')
        {
            // Stores the last element as a digit to CityArray
            if (Cbuffer[2] >= '0' && Cbuffer[2] <= '9')
            {
                CityArray[x][0] = Cbuffer[2] - '0';
                int z = CityArray[x][0];
                // Flips it
                CityArray[0][x] = Cbuffer[2] - '0';
                z = CityArray[0][x];
                // printf("CityArray[%d] is '%d' \n", x, z);
                x++;
            }
        }
        else if (Cbuffer[0] == 'a')
        {
            int y = 1;
            // I know this looks ugly but it's the only way I could think of getting the prices
            if ((Cbuffer[6] >= '0' && Cbuffer[6] <= '9') && (Cbuffer[7] >= '0' && Cbuffer[7] <= '9') &&
                    (Cbuffer[8] >= '0' && Cbuffer[8] <= '9') && (Cbuffer[9] >= '0' && Cbuffer[9] <= '9'))
            {
                for (x = 1; x < 6; x++)
                {
                    for (y; y < 6; y++)
                    {   // converts the char to a int
                        n1 = CityArray[x][6] = Cbuffer[6] - '0';
                        n2 = CityArray[x][7] = Cbuffer[7] - '0';
                        n3 = CityArray[x][8] = Cbuffer[8] - '0';
                        n4 = CityArray[x][9] = Cbuffer[9] - '0';
                    }
                } // sets all converted ints to = cost
                cost = (n1 * 1000) + (n2 * 100) + (n3 * 10) + (n4 * 1);
                x++;
            }
            // Checks where the arc is located and plots the distance of the trip
            if (Cbuffer[2] == '1')
            {
                if (Cbuffer[4] == '2')
                {
                    CityArray[1][2] = cost;
                    CityArray[2][1] = cost;
                }
                else if (Cbuffer[4] == '3')
                {
                    CityArray[1][3] = cost;
                    CityArray[3][1] = cost;
                }
                else if (Cbuffer[4] == '4')
                {
                    CityArray[1][4] = cost;
                    CityArray[4][1] = cost;
                }
                else if (Cbuffer[4] == '5')
                {
                    CityArray[1][5] = cost;
                    CityArray[5][1] = cost;
                }
            }
            else if (Cbuffer[2] == '2')
            {
                if (Cbuffer[4] == '3')
                {
                    CityArray[2][3] = cost;
                    CityArray[3][2] = cost;
                }
                else if (Cbuffer[4] == '4')
                {
                    CityArray[2][4] = cost;
                    CityArray[4][2] = cost;
                }
                else if (Cbuffer[4] == '5')
                {
                    CityArray[2][5] = cost;
                    CityArray[5][2] = cost;
                }
            }
            else if (Cbuffer[2] == '3')
            {
                if (Cbuffer[4] == '4')
                {
                    CityArray[3][4] = cost;
                    CityArray[4][3] = cost;
                }
            else if (Cbuffer[4] == '5')
            {
                    CityArray[4][5] = cost;
                    CityArray[5][4] = cost;
                }
            }
            else if (Cbuffer[2] == '4')
            {
                if (Cbuffer[4] == '5')
                {
                    CityArray[4][5] = cost;
                    CityArray[5][4] = cost;
                }
            }
        }   
    }

    // Prints the array
    int i, j;
    printf("\n\nThe cost list is:\n\n");
    for(i = 0; i < 6;i ++)
    {
        printf("\n\n");
        for(j = 0; j < 6; j++)
        {
            printf("\t%d", CityArray[i][j]);
        }
        printf("\n");
    }

    return 0;
}

你的问题在这里:

            for (x = 1; x < 6; x++)
            {
                for (y; y < 6; y++)
                {   // converts the char to a int
                    n1 = CityArray[x][6] = Cbuffer[6] - '0';
                    n2 = CityArray[x][7] = Cbuffer[7] - '0';
                    n3 = CityArray[x][8] = Cbuffer[8] - '0';
                    n4 = CityArray[x][9] = Cbuffer[9] - '0';
                }
            } // sets all converted ints to = cost
            cost = (n1 * 1000) + (n2 * 100) + (n3 * 10) + (n4 * 1);
            x++;

首先,这里不需要循环;在这里循环意味着您将多次进行转换。 (实际上,更糟糕的是:因为您没有初始化 y,所以您可能根本不会进行转换。如果您激活警告,您会得到一些类似于 "statement with no effect" 的独立 y.)

其次,您将转换后的数字存储在 CityArray[x][6 ... 9] 中,但 6 及以上的索引超出范围。那是未定义的行为。实际上,您会覆盖下一个城市的数据。

第三,你不应该使用 x 作为循环变量和保存城市数量的变量。循环将覆盖数据。 (但是当你移除循环时,这个问题就消失了。)

就这样:

            n1 = Cbuffer[6] - '0';
            n2 = Cbuffer[7] - '0';
            n3 = Cbuffer[8] - '0';
            n4 = Cbuffer[9] - '0';

            cost = (n1 * 1000) + (n2 * 100) + (n3 * 10) + (n4 * 1);

代码还有很多问题。特别是城市和距离的解析非常受限。如果城市的成本不是四位数会怎样?如果第一个城市的数字大于第二个城市,会发生什么情况?

您还可以使用从 ASCII 到城市单位数整数的转换:

        int from = Cbuffer[2] - '0';
        int dest = Cbuffer[4] - '0';

        CityArray[from][dest] = cost;
        CityArray[dest][from] = cost;

这会去掉很多代码。与其硬编码所有可能性,不如将精力花在编写有意义的错误消息上,例如,如果城市的 ID 超出范围。

您还应该考虑使用标准方法来解析输入。 getline 结合 scanf 可能是一个不错的方法。

编辑:下面是输入的示例实现。它最多可以取 10 个城市,由一个可以是数字的字符标识。它对 ca 行的确切格式没有任何限制,并且还会跟踪变量 ncitiy 中实际城市的数量。它接受空行和以 # 开头的行作为非命令。

尽管进行了大量的错误检查,这个程序还是比你的程序短一点。这里是:

#define _GNU_SOURCE

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

#define MAX 10


int find(int array[], int n, int x)
{
    for (int i = 0; i < n; i++) {
        if (array[i] == x) return i;
    }

    return -1;
}

int main(void)
{
    int cost[10][10] = {{0}};       // cost matrix
    int id[MAX];                    // city id; can be any character
    int ncity = 0;                  // number of cities

    char *line = NULL;
    size_t nline = 0;
    int error = 0;

    while (getline(&line, &nline, stdin) != -1) {
        char c1, c2;
        int c;

        if (sscanf(line, " c %c", &c1) == 1) {
            if (find(id, ncity, c1) != -1) {
                fprintf(stderr, "Duplicate city id %c.\n", c1);
                error = 1;
                break;
            } else if (ncity >= MAX) {
                fprintf(stderr, "Maximum number of cities exceeded\n");
                error = 1;
                break;
            } else {
                id[ncity++] = c1;
            }
            continue;
        }

        if (sscanf(line, " a %c %c %d\n", &c1, &c2, &c) == 3) {
            int from = find(id, ncity, c1);
            int dest = find(id, ncity, c2);

            if (from < 0) {
                fprintf(stderr, "Unknown city id %c.\n", c1);
                error = 1;
                break;
            }

            if (dest < 0) {
                fprintf(stderr, "Unknown city id %c.\n", c2);
                error = 1;
                break;
            }

            cost[from][dest] = c;
            cost[dest][from] = c;

            continue;
        }

        if (sscanf(line, " %c", &c1) == 1 && c1 != '#') {
            fprintf(stderr, "Unknown command: %s", line);
            error = 1;
            break;
        }
    }

    free(line);

    if (error) {
        fprintf(stderr, "Errors in input. Aborting.\n");
        exit(1);
    }

    printf("%8s", "");
    for (int j = 0; j < ncity; j++) {
        printf("%8c", id[j]);
    }
    puts("");

    for(int i = 0; i < ncity; i ++)
    {
        printf("%8c", id[i]);
        for (int j = 0; j < ncity; j++) {
            printf("%8d", cost[i][j]);
        }
        puts("");
    }
    puts("");

    return 0;
}