File IO

A file can be defined as a location on the disk where we store logically related data under a same name

In c programming  we can make file in which we can store and retrieve data

Before writing data to a file we first have to define a file and we do this by using the following syntax

FILE *fp ;

Fp = fopen(“file name”,”mode”) ;

In the first line of the syntax we declare a pointer “*fp” which is of FILE type , it is a special type which handles files

Now we use this pointer to open a file , this is very important , weather we want to read or write to a file we first have to open it and we do this by using “fopen” which means “file open”

fopen takes two parameter , one is the file name and other is the mode . Mode can be read , write or append which is represented by keywords “r” , “w” , “a”

after we open the file , we can manipulate the file and then we close the file . Closing of the file is done by writing

fclose( fp ) ;

let us now see a program which creates a file and writes characters to it

#include<stdio.h>

main()

{

FILE *fp;

char c;

printf("Enter Data\nTo finish writing press enter then type ctrl + z to end\n\n");

fp = fopen("f:\\file one.txt","w");

while((c=getchar())!=EOF)

{

putc(c,fp);

}

fclose(fp);

printf("Press Enter To Exit\n");

getch();

}

We have seen how to write characters to a file , now let us see how we can read data from a file we have created

#include<stdio.h>

main()

{

FILE *fp;

char c;

printf("The Contents Of The File\n\n");

fp = fopen("f:\\file one.txt","r");

while((c = getc(fp)) != EOF)

{

printf("%c",c);

}

fclose(fp);

getch();

}

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