FILE VÀ HỆ THỐNG
1. Xóa 1 file dùng Remove

Code:


#include <stdio.h>

int main()
{
remove("d:/urls1.dat");

return 0;
}


2. Xóa 1 File dùng Unlink

Code:


#include <stdio.h>

int main()
{
remove("C:/pete.txt");

return 0;
}


3. Cho biết thông tin FAT

Code:


#include <stdio.h>
#include <dos.h>

void main(void)
{
struct fatinfo fat;

getfatd(&fat);

printf("Sectors per cluster %d\n", fat.fi_sclus);
printf("Clusters per disk %u\n", fat.fi_nclus);
printf("Bytes per cluster %d\n", fat.fi_bysec);
printf("Disk type %x\n", fat.fi_fatid & 0xFF);
}


4. Đếm tần suất 1 kí tự trong 1 file

Code:


# include <stdio.h>
# include <string.h>
main()
{
 FILE *fp;
 char in[100];
 long int freq[257];
 int i;

 printf("\nFile frequency table generator\n\n");

 printf("\nInput file:");
 scanf("%s",in);
 fp=fopen(in,"rb");
 if(fp==NULL)
 {
  printf("\nCould not open input file.Aborting\n");
  return 1;
 }
 for(i=0;i<257;i++)
  freq[i]=0;
 while(i=fgetc(fp),i!=EOF)
 {
  freq[i]++;
 }
 fcloseall();
 fp=fopen("count.txt","w");
 fprintf(fp,"\nCharacter frequency table of %s\n",in);
 fprintf(fp,"\nCharacter ASCII frequency\n\n");
 for(i=0;i<256;i++)
 {
  if(i==26)
  {
  fprintf(fp,"\t    26\t  %ld\n",freq[26]);
  }
  else if(i==9)
  {
  fprintf(fp,"\t    9\t  %ld",freq[9]);
  }
  else if(i<10)
  {
  fprintf(fp,"%c\t    %d\t  %ld\n",i,i,freq[i]);
  }
  else if(i<100)
  {
  fprintf(fp,"%c\t    %d\t  %ld\n",i,i,freq[i]);
  }
  else
  {
  fprintf(fp,"%c\t    %d\t  %ld\n",i,i,freq[i]);
  }
 }
 
 fcloseall();
 printf("\nFrequency table copied to count.txt\n");
}


5. Đọc nội dung 1 file

Code:


#include <stdio.h>

void main(void)
{
FILE *fp;
char ch;

fp = fopen("websites.txt","r");
ch = getc(fp);
while(ch!=EOF)
{
putchar(ch);
ch = getc(fp);
}
printf("\n\n");
}


6. Chọn ổ đĩa trong DOS

Code:


#include <stdio.h>
#include <dir.h>

void main(void)
{
int drives;

drives = setdisk(3);
printf("The number of available drives is %d\n", drives);
}


7.Chọn ổ đĩa trong WINS

Code:


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

void main(void)
 {
    char szBuffer[MAX_PATH+100];
    UINT nDrive, AvailDrive = 0;
    int dwLogicalDrives = GetLogicalDrives();
    DWORD Success;

    printf("Number of logical drives: %d\n", dwLogicalDrives);
       for (nDrive = 0; nDrive < 32; nDrive++)
      {
         if (dwLogicalDrives & (1 << nDrive))
          { // Is drive available?
            AvailDrive++;
            // Get disk information.
            wsprintf(szBuffer, "%c:\\", nDrive+'A', '\0');
            // Print out information.
            if(SetCurrentDirectory(szBuffer))
              printf("%s Is Now Current\n", szBuffer);
           else
              printf("Could not set %s as the current drive\n", szBuffer);
          }
      }
      printf("Number of drives available: %d\n", AvailDrive);

 }


8. Cho biết kích thước 1 file

Code:


#include <stdio.h>
#include <io.h>
#include <fcntl.h>
#include <sys\stat.h>

int main()
{
int fp;

long file_size;

if ((fp = open("f:/cprojects/urls.txt", O_RDONLY)) == -1)
printf("Error opening the file \n");
else
{
file_size = filelength(file_handle);
printf("The file size in bytes is %ld\n", file_size);
close(fp);
}
return 0;
}