EOF[End Of File]

• End of file[EOF] is a condition in computer operating system where no more data can be read from a data source(file or stream).
• EOF is actually a macro defined as an integer with a negative value(normally -1).
• EOF is normally returned by functions that perform read operations to denote either an error or end of input. It is important to ensure you use an integer to store the return code from these functions, even if the function appears to be returning a char, such as getchar() or fgetc().
• We cannot stop the program by directly giving -1. when you write '-1', you do not write the VALUE -1, but the character string { '-', '1' } your program will not stop, except if you type ctrl+D under linux, or ctrl+Z+enter under windows. 

EOF is

1. Not a character
2. A value that exists at the end of  a file
3. A value that could exist at the middle of  a file

Example Program to find the EOF value:



/*************Program1***********/
#include<stdio.h>
int main()
{
    int ch=getchar();
    printf("%d",ch);
    return;
}
---------------------------------------
/*************Program2***********/
#include<stdio.h>
int main()
{
    printf("%d",EOF);
    return;
}

In Windows if you enter the keys Control + Z you get EOF, in Linux it is Control + D
Output: -1