A file represents a sequence of bytes of the computer hard disk. Files are used to store data permanently.

In C programming, the structure pointer of file type is used to do file I/O

FILE *fileptr;

Functions used in file handling

• fopen() create a new file or open a existing file
• fclose() closes a file
• getc() reads a character from a file
• putc() writes a character to a file
• fscanf() reads a set of data from a file
• fprintf() writes a set of data to a file
• getw() reads a integer from a file
• putw() writes a integer to a file
• fseek() set the position to desire point
• ftell() gives current position in the file
• rewind() set the position to the beginning point

Different modes used in file handling

• r opens a text file in reading mode
• w opens or create a text file in writing mode.
• a opens a text file in append mode
• r+ opens a text file in both reading and writing mode
• w+ opens a text file in both reading and writing mode
• a+ opens a text file in both reading and writing mode
• rb opens a binary file in reading mode
• wb opens or create a binary file in writing mode
• ab opens a binary file in append mode
• rb+ opens a binary file in both reading and writing mode
• wb+ opens a binary file in both reading and writing mode
• ab+ opens a binary file in both reading and writing mode

Open or Create file

The fopen() function is used to open or create any file.

Syntax of fopen() function -

FILE *fileptr = NULL;
fileptr = fopen(const char *filename, const char *mode);

filename is the name of file to open and mode represent purpose (read, write, append etc..) of opening any file.fileptr is the FILE pointer which point to file.

Closing a File

fclose() function is used to close an already opened file in program.

Syntax -

int flose(FILE *fileptr);

flclose() function closed the file and returns 0 on success of EOF char if there is an error in closing the file.The EOF is a character constant used to check end of file, defined in stdio.h header file.

Example on File Handling in C using getc() & putc()

We already discussed the functions, modes used in file operations. Here is the complete working example -

#include<stdio.h>
#include<conio.h>
int main()
{
 FILE *fp;
 char ch;
 int count = 0;
 
 fp = fopen("cppbuzz.txt", "w");
 printf("Enter 10 characters followed by enter - \n ");
 while(count <10) {
 ch = getchar();     
 putc(ch,fp);
 count++;
 } 
 
 fclose(fp);
 
 fp = fopen("cppbuzz.txt", "r");
 while( (ch = getc(fp)) != EOF)
 printf("%c",ch);
 fclose(fp);
 return 0;
}   

Example on File Handling in C using fprintf() & fscanf()

We already discussed the functions, modes used in file operations. Here is the complete working example -

 #include<stdio.h>
#include<conio.h>
struct school
{
 char name[10];
 int fees;
};
int main()
{
 struct school xavior;
 FILE *fptrAppend,*fptrRead;
 
 char temp_name[10];
 int temp_fees;
 
 fptrAppend = fopen("CppBuzz.txt", "a");
 fptrRead = fopen("CppBuzz.txt", "r");
 
 printf("Enter School's Name :");
 scanf("%s", xavior.name);
 
  printf("Enter School's Fees :");
 scanf("%d", &xavior.fees);
 
 fprintf(fptrAppend,"%s %d", xavior.name, xavior.fees);
 fclose(fptrAppend);
 
 do
 {
 fscanf(fptrRead,"%s %d", xavior.name, &xavior.fees);
 printf("%s %d", xavior.name, xavior.fees);
 }
 while(!feof(fptrRead));
 return 0;
}