How do you read scanf until EOF in C

Question

I have this but once it reaches the supposed EOF it just repeats the loop and scanf again   int main void            char words 16            while scanf   15s   words     1             printf   s n   words            return 0

User · Answer

You need to check the return value against EOF, not against 1.

Note that in your example, you also used two different variable names, words and word, only declared words, and didn't declare its length, which should be 16 to fit the 15 characters read in plus a NUL character.

User · Answer

For C users  this will also work  while   gets str     NULL

User · Answer

Scanf is pretty much always more trouble than it s worth   Here are two better ways to do what you re trying to do   This first one is a more-or-less direct translation of your code   It s longer  but you can look at it and see clearly what it does  unlike with scanf    include  lt stdio h gt   include  lt ctype h gt  int main void        char buf 1024    p   q      while  fgets buf  1024  stdin                 p   buf          while   p                        while   p  amp  amp  isspace  p   p                q   p              while   q  amp  amp   isspace  q   q                 q     0               if  p    q                  puts p               p   q                      return 0      And here s another version   It s a little harder to see what this does by inspection  but it does not break if a line is longer than 1024 characters  so it s the code I would use in production    Well  really what I would use in production is tr -s    space      n   but this is how you implement something like that     include  lt stdio h gt   include  lt ctype h gt  int main void        int ch  lastch     0       while   ch   getchar       EOF                if   isspace ch               putchar ch           if   isspace lastch               putchar   n            lastch   ch            if  lastch      0   amp  amp   isspace lastch           putchar   n        return 0

User · Answer

Your code loops until it reads a single word  then exits   So if you give it multiple words it will read the first and exit  while if you give it an empty input  it will loop forever   In any case  it will only print random garbage from uninitialized memory   This is apparently not what you want  but what do you want   If you just want to read and print the first word  if it exists   use if   if  scanf   15s   word     1      printf   s n   word     If you want to loop as long as you can read a word  use while   while  scanf   15s   word     1      printf   s n   word     Also  as others have noted  you need to give the word array a size that is big enough for your scanf   char word 16     Others have suggested testing for EOF instead of checking how many items scanf matched   That s fine for this case  where scanf can t fail to match unless there s an EOF  but is not so good in other cases  such as trying to read integers   where scanf might match nothing without reaching EOF  if the input isn t a number  and return 0   edit  Looks like you changed your question to match my code which works fine when I run it -- loops reading words until EOF is reached and then exits   So something else is going on with your code  perhaps related to how you are feeding it input as suggested by David

User · Answer

I guess best way to do this is      int main         char str 100       scanf    EOF   str       printf   s  str       return 0

User · Answer

Try   while scanf   15s   words     EOF    You need to compare scanf output with EOF   Since you are specifying a width of 15 in the format string  you ll read at most 15 char  So the words char array should be of size 16   15  1 for null char   So declare it as   char words 16

User · Answer

Man  if you are using Windows  EOF is not reached by pressing enter  but by pressing Crtl Z at the console  This will print   Z   an indicator of EOF   The behavior of functions when reading this  the EOF or Crtl Z     Function              Output  scanf                 EOF gets  lt variable gt        NULL feof stdin            1 getchar               EOF

[c] How do you read scanf until EOF in C?

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