Binary Data Files

1. Binary Data Files CHAPTER 7

2. Chapter 8: Binary Data Files Objectives: You’ll learn about; • Introduction • Fundamentals of binary data files • Processing binary files • Files with mixed type data • Related example Chapter 7 : Binary Data Files

3. What is a Binary File? • In the binary data file, the information will be stored in groups of binary digits. Each binary digit is a zero or one and eight binary digits grouped together is a byte. Chapter 7 : Binary Data Files

4. Content inside Binary File: Example ## source file:#### Four score and seven years ago,## our fathers brought forth on this continent## a new nation, conceived in liberty## and dedicated to the proportion that## all men are created equal.## Chapter 7 : Binary Data Files

5. Content inside Binary File: Example (con’t) ## binary file:#### 01000110 01101111 01110101 01110010 00100000## 01110011 01100011 01101111 01110010 01100101## 00100000 01100001 01101110 01100100 00100000## 01110011 01100101 01110110 01100101 01101110## 00100000 01111001 01100101 01100001 01110010## 01110011 00100000 01100001 01100111 01101111## 00101100 00001010 01101111 01110101 01110010## 00100000 01100110 01100001 01110100 01101000## 01100101 01110010 01110011 00100000 01100010## 01110010 01101111 01110101 01100111 01101000## 01110100 00100000 01100110 01101111 01110010## 01110100 01101000 00100000 01101111 01101110## 00100000 01110100 01101000 01101001 01110011## 00100000 01100011 01101111 01101110 01110100## 01101001 01101110 01100101 01101110 01110100## 00001010 01100001 00100000 01101110 01100101## 01110111 00100000 01101110 01100001 01110100## 01101001 01101111 01101110 00101100 00100000## 01100011 01101111 01101110 01100011 01100101## 01101001 01110110 01100101 01100100 00100000## 01101001 01101110 00100000 01101100 01101001## 01100010 01100101 01110010 01110100 01111001## 00001010 01100001 01101110 01100100 00100000## 01100100 01100101 01100100 01101001 01100011## 01100001 01110100 01100101 01100100 00100000## 01110100 01101111 00100000 01110100 01101000## 01100101 00100000 01110000 01110010 01101111## 01110000 01101111 01110011 01110100 01101001## 01101111 01101110 00100000 01110100 01101000## 01100001 01110100 00001010 01100001 01101100## 01101100 00100000 01101101 01100101 01101110## 00100000 01100001 01110010 01100101 00100000## 01100011 01110010 01100101 01100001 01110100## 01100101 01100100 00100000 01100101 01110001## 01110101 01100001 01101100 00101110 00001010## Chapter 7 : Binary Data Files

6. Content inside Binary File: Example (con’t) ## decoded binary:#### Four score and seven years ago,## our fathers brought forth on this continent## a new nation, conceived in liberty## and dedicated to the proportion that## all men are created equal. Chapter 7 : Binary Data Files

7. Binary File Binary files have two features that distinguish them from text files: • Can jump instantly to any record in the file, and change the contents of a record anywhere in the file at any time. • Binary files also usually have faster read and write times than text files. It is because a binary image of the record is stored directly from memory to disk (or vice versa). In a text file, everything has to be converted back and forth to text, and this takes time. Chapter 7 : Binary Data Files

8. Binary File • Declared exactly the same way as a text file • Used fopen and fclose • Second argument (wb, rb) – b for binary Chapter 7 : Binary Data Files

9. Binary File : fwrite() • fwrite moves the block of bytes from memory to the file. • Used fwrite with four arguments: • Address of the first memory cell to be copied to file • No of bytes to copied to file • Number of values • 1 – one integer at a time • Array size - Entire size of array • File pointer to the file being created Chapter 7 : Binary Data Files

10. Binary File : Example 1 – creating even integers – fwrite() #include <stdio.h> void main(){ FILE *binaryp; inti; binaryp=fopen("nums.bin","wb"); for (i=2;i<500;i+=2) fwrite(&i,sizeof(int),1,binaryp); fclose(binaryp); //printf("An integer requires %d bytes", sizeof(int)); - samples to indicate bytes occupied } Chapter 7 : Binary Data Files

11. Binary File : fread() • Used fread with four arguments: • a memory address • the number of bytes to read per block • the number of blocks to read • the file variable • Example: • Thus, the line fread(&r,sizeof(struct rec),1,f); says to read 12 bytes (the size of rec) from the file f (from the current location of the file pointer) into memory address &r. One block of 12 bytes is requested. • It would be just as easy to read 100 blocks from disk into an array in memory by changing 1 to 100. Chapter 7 : Binary Data Files

12. Binary File : Example 1- fread() How to read Binary Data File in C (Sequentially) { /* 1 - Additional "b" for fopen() 2 - Usage of fread() instate of fscanf */...fp = fopen(i_filename, "rb"); // read a binary file ("r" and "b").../* loop until all data keep into array */while( (!feof(fp))){ /*fscanf(fp, "%f", &value); you can not use this any more for binary files. Now you have have to use fread() */ fread(&value, sizeof(int), 1, fp); ... } Chapter 7 : Binary Data Files

13. Binary File : Example 2- fread() #include <stdio.h> void main(){ FILE *binaryp; inti; binaryp=fopen("nums.bin","rb"); for (i=2;i<500;i+=2){ fread(&i,sizeof(int),1,binaryp); printf("%d\n",i); } fclose(binaryp); } Chapter 7 : Binary Data Files

14. Summary Chapter 7 : Binary Data Files

15. A sequence arbitrary bytes of structured data. • Not in human readable form. IMPORTANT!! A BINARY FILE can ONLY be created from within a program. A binary file CANNOT be viewed by an editor. To view the contents of a binary file is to write a program (or subprogram) to read each structure and format them to screen. BINARY FILES Chapter 7 : Binary Data Files