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Old 12-18-2005, 05:17 PM   #1
exvor
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Registered: Jul 2004
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EOF and \n


Ok this is confusing me but its probably a simple thing.
in the below code is a program that simulates the cat program.

Now why when running the program does it create a newline char even tho one is not put in when the printing of all the charecters in the file is compleate?

Code:
 
#include<stdio.h> 
#include<stdlib.h> 


int main(int argc, char *argv[]) 
{ 
     FILE *my_file; 
      
     char test;   //charecter to test for EOF and printing. 
 
     
    if (argv[1] == NULL) 
       { 
          printf("Usage is mycat <text file> at this time there are no options\n"); 
          return 0; 
       } 
    my_file = fopen(argv[1],"r"); 
    
    if (my_file == NULL)
       { 
         printf("Error opening file\n");
         return 0; 
       } 
    
   
    do 
       { 
         test = fgetc(my_file); 
         if ( test != EOF) 
               printf("%c",test); 
         } 
    while( test != EOF); 
    fclose(my_file); 
    
    
    return 0; 
}

the file test contains the following text
Code:
cat cat cat mouse
ok so no return in that line of txt "NOTE: when posting on the forem its adding line below the text but this isnt present in the actual file.

here is the program output

Code:
 
user@linux$ ./mycat test
cat cat cat mouse
user@linux$ 
user@linux$ cat test 
cat cat cat mouse
user@linux$

Last edited by exvor; 12-18-2005 at 05:19 PM.
 
Old 12-18-2005, 06:35 PM   #2
Berhanie
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Your editor inserted the newline without your knowledge:
Code:
cat -A test_file
The output will be
Quote:
cat cat cat mouse$
The "$" indicates a newline.
 
Old 12-23-2005, 12:26 AM   #3
exvor
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Registered: Jul 2004
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Original Poster
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What exactly is adding the newline charecter? Is it when the fopen function cals the file and inserts it into the data stream that i give it or is it somewhere else in the code? Not that its causeing an issue I just noticed it when I was messign around. I actually wrote in a newline charecter to be printed when the EOF was reached and saw that 2 of them were being added that is when I started wondering about this.
 
Old 12-23-2005, 09:06 AM   #4
Berhanie
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Depending on how you created the file, the newline was probably added by the editor you used. If you don't want the newline, you can do something like:
Code:
echo -n cat cat cat mouse > test_file
Now, if you do a
Code:
cat -A test_file
you should see
Quote:
cat cat cat mouse
Note the lack of a newline.

Last edited by Berhanie; 12-23-2005 at 09:08 AM.
 
Old 12-27-2005, 02:20 PM   #5
exvor
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Registered: Jul 2004
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Original Poster
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Ohh your right lol. Silly editors.
 
  


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