C++ 避免在C编程中为连接分配大量内存

所提供的代码从文本文件中读取行，并将它们存储在动态分配的称为行的2D数组中(该模式总是在第32767行之后重复).然后，它连接特定的行(行[j]、行[k]、行[m])，并在输出文件中打印结果.问题是我的input.txt文件太大了，以至于我的PC无法处理这个-100 GB.因为使用Malloc时，我为2D数组分配了如此多的内存，以至于我的硬盘驱动器已满.有没有可能更改我的代码，这样我就不必分配这么多内存了？谢谢你的帮助！

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

#define MAX_LINE_LENGTH 300          // specifies the maximum length of a line in the input file
#define MAX_LINES 500000000          // specifies the maximum number of lines of the input file

int main()
{
   // Open the file
   FILE *fp = fopen("input.txt", "r");
   if (fp == NULL)
   {
       printf("Failed to open the file.\n");
       return 1;
   }


   // Allocate memory for lines
   char **lines = (char **)malloc(MAX_LINES * sizeof(char *));
   if (lines == NULL)
   {
       printf("Failed to allocate memory for lines.\n");
       fclose(fp);
       return 1;
   }

   for (int i = 0; i < MAX_LINES; i++)
   {
       lines[i] = (char *)malloc(MAX_LINE_LENGTH * sizeof(char));
       if (lines[i] == NULL)
       {
           printf("Failed to allocate memory for line %d.\n", i);
           // Free previously allocated lines
           for (int j = 0; j < i; j++)
           {
               free(lines[j]);
           }
           free(lines);
           fclose(fp);
           return 1;
       }
   }

   // Reset file pointer to the beginning
   fseek(fp, 0, SEEK_SET);

   // Read lines from the file and store them in lines array
   int lineIndex = 0;
   char line[MAX_LINE_LENGTH];
   while (fgets(line, sizeof(line), fp) != NULL)
   {
       // Remove newline character from the end of the line
       if (line[strlen(line) - 1] == '\n')
           line[strlen(line) - 1] = '\0';
       strcpy(lines[lineIndex], line);
       lineIndex++;
   }

   fclose(fp);

   // Create output file
   FILE *outputFile = fopen("output.txt", "w");
   if (outputFile == NULL)
   {
       perror("Error creating output file");
       // Free allocated lines
       for (int i = 0; i < MAX_LINES; i++)
       {
           free(lines[i]);
       }
       free(lines);
       return 1;
   }
   int i=1;
   int j=5;         //begin Permno number
   int k=10927;     //begin PRC date
   int m=21849;     //begin DLRETX data
   int count=0;

   int jj=10923;    // end PERNMO data
   int kk=21846;    // end PRC data
   int mm=32767;    // end DLRETX data
   int count_whileLoop=0;


   // Append lines
   for (i,j,k,m;  j<=jj,k<=kk,m<=mm;  i++,j++,k++,m++)
   {
       fprintf(outputFile, "%s%s%s\n", lines[j], lines[k], lines[m]);

   }

   // Free allocated memory
   for (int i = 0; i < MAX_LINES; i++)
   {
       free(lines[i]);
   }
   free(lines);

   // Close the output file
   fclose(outputFile);

   return 0;
}