C 读取二进制数文件会丢弃第一个字符

Question

Can anyone help me understand why the first char read from the file is dropped when I increase the file size to be > 19 rows?

When I run this with < 20 rows it works perfect, reads the input and dumps it. when I add a 20th row the first row of input drops the leading char when I print the array.

Im lost. :)

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

int main () {

  int i, j = 0;
  FILE *pFile;
  char string[20][12];
  char file_contents_resultset[20][12];
  

  pFile = fopen("sonar.txt", "r");
  if (pFile == NULL)
    {
      printf ("error opening file");
      return 0;
    }
  // Load 20 row of input into in an array and store a copy
  for (i = 0; i < 20; i++)
    {
      fscanf (pFile, "%12s", &string[i]);
      strcpy (file_contents_resultset[i], string[i]);
    }

  //Dump the first 5 rows of the array
  printf ("Dump array contents \n");
  for (i = 0; i < 5; i++)
    {
      for (j = 0; j < 12; j++)
        {
          printf ("%c", file_contents_resultset[i][j]);
        }
      printf ("\n");
    }

  fclose (pFile);

  return 0;
};

This is my input file.

000110010001
101000110000
000110010111
100011100010
111001100001
001010001010
010100100101
011000010000
111111011010
001111011101
011011010010
001100010101
001010101100
000000000000
100010111111
100100110011
111100100001
011110001110
000110100101
011101111001

and this is the output

Dump array contents 
00110010001
101000110000
000110010111
100011100010
111001100001

and this is the output if I delete the 20th row of input in the input file. Note the first char is no longer dropped.

Dump array contents 
000110010001
101000110000
000110010111
100011100010
111001100001

Answer 1

Your one of the arrays you use for reading is redundant. You can use only string[][] or only file_contents_resultset[][] .

I found that your problem is in the strcpy() call. Reading from the buffer is fine, but strcpy() seems to copy a blank character in the memory location of file_contents_resultset[0][0] .

So to fix it by keeping as much of the program intact i did:

// ...
// stores only one row at a time
char string[12];
// ...

for (int i = 0; i < 20; i++) {
    fscanf(pFile, "%12s", &string);
    strcpy(file_contents_resultset[i], string);
}

// ...
}

If you want to be more concise and save memory, you can remove string altogether and just write:

// ...
// char string[12];
char file_contents_resultset[20][12];
// ...

// brackets in loops and other blocks can be omitted
// if the block is just 1 line long. 
for (int i = 0; i < 20; i++)
   fscanf(pFile, "%12s", &file_contents_resultset[20][12]);
// ...