File I/O

File I/O

• To perform operation on file c language provides us different functions
• These functions are declared in header file stdio.h

Types of Files

• Text files
• Binary files

fopen()

• It is used to open a file
• This function returns a FILE pointer if successful.
• It returns NULL if cannot open.
• A global variable errno is set to indicate the error.
Syntax:
FILE* fopen( char *filename, char *mode) 
• filename − name of the file to be opened.
• mode − file access mode.

File Modes

  #include<stdio.h>
  main()
  {
    FILE *fp;
    fp=fopen("ccit.txt","r");
    if(fp = = NULL)
        printf("File dos'nt exists...");
    else
    {
        printf("File  exists...");
        fclose(fp);
    }
  }

File  exists...
  

fclose()

• It is used to close a file.
• It will close the specified file.
• This method returns zero if the FILE is successfully closed. On failure, EOF is returned.
• FILE close will flush out all the entries from buffer if file is open in write mode.

fclose()

• It is used to close all open files.
• The fcloseall() function closes all of the calling programs open FILES.
• Buffered output for each File is written before it is closed if file is opened in write mode.
• This function returns 0 if all files were successfully closed; on error, EOF is returned.