如何从C中的文件中的列表中制作邻接矩阵

Question

嘿，我想从 c 中的文件的列表中创建一个邻接矩阵，但我不知道该怎么做。 到目前为止，这是我的代码：

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

typedef struct value {
  int num;
  char start_vertex[250];
  char destination_vertex[250];
} value;

int main()
{
  const int nLines = 43; // number of lines in my text file
  FILE * fptr;
  value * valuesPtr = malloc(sizeof(value) * nLines);

  if (!valuesPtr) {
    puts("cannot allocate memory");
    return -1;
  }

  if((fptr = fopen("energy.txt", "r")) == NULL)
  {
    perror("Error opening file");
    return -1;
  }

  for(int i = 0; i < nLines; i++ )
  {
      if (fscanf(fptr, "%249s %249s %d",
                 valuesPtr[i].start_vertex,
                 valuesPtr[i].destination_vertex,
                 &valuesPtr[i].num) != 3) {
        printf("errored file line %d\n", i);
        break;
      }

      printf("\nStart vertex: %s \nDestination vertex: %s \nWeight: %d\n\n",
             valuesPtr[i].start_vertex, valuesPtr[i].destination_vertex, valuesPtr[i].num);
  }
  free(valuesPtr);
  fclose(fptr);

  return 0;
}

能量文件里面有以下内容

York    Hull    60
Leeds   Doncaster   -47
Liverpool   Nottingham  161
Manchester  Sheffield   61
Reading Oxford  -43
Oxford  Birmingham  103
Birmingham  Leicester   63
Liverpool   Blackpool   79
Carlisle    Newcastle   92
Nottingham  Birmingham  77
Leeds   York    39
Glasgow Edinburgh   74
Moffat  Carlisle    65
Doncaster   Hull    76
Northampton Birmingham  90
Leicester   Lincoln 82
Sheffield   Birmingham  122
Lincoln Doncaster   63
Sheffield   Doncaster   29
Bristol Reading 130
Hull    Nottingham  145
Blackpool   Leeds   116
Birmingham  Bristol 139
Manchester  Leeds   64
Carlisle    Blackpool   140
Leicester   Northampton -61
Newcastle   York    135
Glasgow Moffat  -28
Leicester   Sheffield   100
Carlisle    Liverpool   -30
Birmingham  Manchester  129
Oxford  Bristol 116
Leeds   Hull    89
Edinburgh   Carlisle    154
Nottingham  Sheffield   61
Liverpool   Manchester  56
Carlisle    Glasgow 50
Sheffield   Lincoln 74
York    Doncaster   55
Newcastle   Edinburgh   177
Leeds   Sheffield   53
Northampton Oxford  68
Manchester  Carlisle    20

总共有 21 个城市（节点），文件中的每一行显示从一个城市移动到另一个城市（边缘）需要多少能量。我想将数据保存到一个矩阵中，以便以后进行进一步计算。

Answer 1

如果要将值存储在数组中，请创建数组，然后将值复制到其中。

  int num[nLines];
  char start_vertex[nLines][250];
  char destination_vertex[nLines][250];

复制数据，你可以使用strcpy()将字符串复制到c中的字符串

for(int i = 0; i < nLines; i++ ) {
   if (fscanf ...
   ...
   num[i] = valuesPtr[i].num;
   strcpy(start_vertex[i], valuesPtr[i].start_vertex);
   strcpy(destination_vertex[i], valuesPtr[i].destination_vertex);
   ...
}

测试：

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

typedef struct value {
  int num;
  char start_vertex[250];
  char destination_vertex[250];
} value;

int main()
{
  const int nLines = 43; // number of lines in my text file
  FILE * fptr;
  value * valuesPtr = malloc(sizeof(value) * nLines);

  if (!valuesPtr) {
    puts("cannot allocate memory");
    return -1;
  }

  if((fptr = fopen("text.txt", "r")) == NULL)
  {
    perror("Error opening file");
    return -1;
  }

  // The array for storing all num that you get from energy file
  int num[nLines];
  // The array of string for storing all start_vertex that you get from energy file
  char start_vertex[nLines][250];
  // The array of string for storing all destination_vertex that you get from energy file
  char destination_vertex[nLines][250];

  for(int i = 0; i < nLines; i++ )
  {
      if (fscanf(fptr, "%249s %249s %d",
                 valuesPtr[i].start_vertex,
                 valuesPtr[i].destination_vertex,
                 &valuesPtr[i].num) != 3) {
        printf("errored file line %d\n", i);
        break;
      }

      num[i] = valuesPtr[i].num;
      strcpy(start_vertex[i], valuesPtr[i].start_vertex);
      strcpy(destination_vertex[i], valuesPtr[i].destination_vertex);

      printf("\nStart vertex: %s \nDestination vertex: %s \nWeight: %d\n\n",
             valuesPtr[i].start_vertex, valuesPtr[i].destination_vertex, valuesPtr[i].num);

      printf("\nStart vertex: %s \nDestination vertex: %s \nWeight: %d\n\n",
             start_vertex[i], destination_vertex[i], num[i]);
  }
  free(valuesPtr);
  fclose(fptr);

  return 0;
}