What is EOF in the C programming language

Question

How do you get to see the last print  In other words what to put in for EOF  I checked the definitions and it says EOF is -1    And if you enter Ctrl-D you won t see anything    include  lt stdio h gt   int main      int c   while  c   getchar      EOF       printf   d n   c       printf   d - at EOF n   c

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Couple of typos   while  c   getchar      EOF   in place of   while  c   getchar      EOF    Also getchar   treats a return key as a valid input  so you need to buffer it too EOF is a marker to indicate end of input  Generally it is an int with all bits set     include  lt stdio h gt  int main      int c   while  c   getchar      EOF       if  getchar      EOF       break    printf    d n   c        printf   d  u  x- at EOF n   c   c  c       prints   49 50 -1 4294967295 ffffffff- at EOF  for input    1 2  lt ctrl-d gt

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EOF means end of file  It s a sign that the end of a file is reached  and that there will be no data anymore   Edit   I stand corrected  In this case it s not an end of file  As mentioned  it is passed when CTRL d  linux  or CTRL z  windows  is passed

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On Linux systems and OS X  the character to input to cause an EOF is Ctrl-D   For Windows  it s Ctrl-Z   Depending on the operating system  this character will only work if it s the first character on a line  i e  the first character after an Enter  Since console input is often line-oriented  the system may also not recognize the EOF character until after you ve followed it up with an Enter   And yes  if that character is recognized as an EOF  then your program will never see the actual character  Instead  a C program will get a -1 from getchar

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nput from a terminal never really  ends   unless the device is disconnected   but it is useful to enter more than one  file  into a terminal  so a key sequence is reserved to indicate end of input  In UNIX the translation of the keystroke to EOF is performed by the terminal driver  so a program does not need to distinguish terminals from other input files  By default  the driver converts a Control-D character at the start of a line into an end-of-file indicator  To insert an actual Control-D  ASCII 04  character into the input stream  the user precedes it with a  quote  command character  usually Control-V   AmigaDOS is similar but uses Control-  instead of Control-D   In Microsoft s DOS and Windows  and in CP M and many DEC operating systems   reading from the terminal will never produce an EOF  Instead  programs recognize that the source is a terminal  or other  character device   and interpret a given reserved character or sequence as an end-of-file indicator  most commonly this is an ASCII Control-Z  code 26  Some MS-DOS programs  including parts of the Microsoft MS-DOS shell  COMMAND COM  and operating-system utility programs  such as EDLIN   treat a Control-Z in a text file as marking the end of meaningful data  and or append a Control-Z to the end when writing a text file  This was done for two reasons                Backward compatibility with CP M  The CP M file system only recorded the lengths of files in multiples of 128-byte  records   so by convention a Control-Z character was used to mark the end of meaningful data if it ended in the middle of a record  The MS-DOS filesystem has always recorded the exact byte-length of files  so this was never necessary on MS-DOS      It allows programs to use the same code to read input from both a terminal and a text file

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include  lt stdio h gt   int main         int c      while  c   getchar       EOF             putchar c                 printf   d  at EOF n   c       modified the above code to give more clarity on EOF  Press Ctrl d and putchar is used to print the char avoid using printf within while loop

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You should change your parenthesis to  while  c   getchar       EOF    Because the     operator has a lower precedence than the      operator  Then you will get the expected results  Your expression is equal to  while  c    getchar     EOF     You are getting the two 1 s as output  because you are making the comparison  c  EOF   This will always become one for the character you entered and then the   n  that follows by hitting return  Except for the last comparison where c really is EOF it will give you a 0   EDIT about EOF  EOF is typically -1  but this is not guaranteed by the standard  The standard only defines about EOF in section 7 19 1      EOF which expands to an integer   constant expression  with type int and   a negative value  that is returned by   several functions to indicate   end-of-file  that is  no more input   from a stream    It is reasonable to assume that EOF equals -1  but when using EOF you should not test against the specific value  but rather use the macro

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to keep it simple  EOF is an integer type with value -1  Therefore  we must use an integer variable to test EOF

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The value of EOF is a negative integer to distinguish it from  char  values that are in the range 0 to 255   It is typically -1  but it could be any other negative number     according to the POSIX specs  so you should not assume it is -1   The  D character is what you type at a console stream on UNIX Linux to tell it to logically end an input stream   But in other contexts  like when you are reading from a file  it is just another data character   Either way  the  D character  meaning end of input  never makes it to application code   As  Bastien says  EOF is also returned if getchar   fails   Strictly speaking  you should call ferror or feof to see whether the EOF represents an error or an end of stream   But in most cases your application will do the same thing in either case

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include  lt stdio h gt   int main         int c      while  c   getchar       EOF      precedence of    is greater than    so use braces         printf   d n   c             printf   d - at EOF n   c       I think this is right way to check value of EOF   And I checked the output   For INPUT  abc and Enter I got OUTPUT  97 98 99 10    the ASCII values   For INPUT Ctrl-D I got OUTPUT  -1 - at EOF  So I think -1 is the value for EOF    Try other inputs instead of Ctrl-D  like Ctrl-Z  I think it varies from compiler to compiler

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int c   while  c   getchar      10        if  getchar      EOF           break        printf    d n   c

[c] What is EOF in the C programming language?

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