Viewing the contents of a file - C File

C examples for File:File Operation

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Description

Viewing the contents of a file

Demo Code

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

#define DISPLAY     80                                // Length of display line
#define PAGE_LENGTH 20                                // Lines per page

int main(int argc, char *argv[])
{
  char filename[FILENAME_MAX];                        // Stores the file path
  FILE *pfile = NULL;                                 // File pointer

  unsigned char buffer[DISPLAY/4 - 1];                // File input buffer

  size_t count = 0;                                   // Count of characters in buffer

  int lines = 0;                                      // Number of lines displayed

  if(argc == 1)                                       // No file name on command line?
  {//  w  ww.jav a 2  s .c  om
    printf("Please enter a filename: ");            // Prompt for input
    fgets(filename, FILENAME_MAX, stdin);             // Get the file name entered

    int len = strnlen(filename, sizeof(filename));
    if(filename[len - 1] == '\n')
      filename[len - 1] = '\0';
  }
  else
    strcpy(filename, argv[1]);                        // Get 2nd command line string

  pfile = fopen(filename, "rb");
  if(pfile == NULL)                 // Open for binary read
  {
    printf("Sorry, can't open %s.\n", filename);
    return -1;
  }
  setvbuf(pfile, NULL, _IOFBF, BUFSIZ);               // Buffer file input

  while(!feof(pfile))                                 // Continue until end of file
  {
    count = fread(buffer, 1, sizeof(buffer), pfile);

    for(size_t i = 0 ; i < sizeof(buffer) ; ++i){
      if(i < count)
        printf("%02X ", buffer[i]);
      else
        printf("   ");
    }
    printf("| ");                                   // Output separator

    // Now display buffer contents as characters
    for(size_t i = 0 ; i < count ; ++i)
      printf("%c", isprint(buffer[i]) ? buffer[i]:'.');

    printf("\n");                                   // End the line

    if(!(++lines % PAGE_LENGTH))                      // End of page?
     if(toupper(getchar())=='E')                      // Wait for Enter
        break;
  }

  fclose(pfile);                                
  pfile = NULL;
  return 0;
}

Result


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