unexpected ( unwanted ) output in a file

This is a discussion on unexpected ( unwanted ) output in a file within the C Programming forums, part of the General Programming Boards category; hi, again. I have another problem, this time while writing in a file the lines of another program. a certain ...

  1. #1
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    Apr 2004
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    Question unexpected ( unwanted ) output in a file

    hi, again. I have another problem, this time while writing in a file the lines of another program.

    a certain file .h , which will be told to open by a file .c ( first argument ),
    and, from that file .h , i will copy each line into another file .txt ( second argument )

    if the file .h (mentioned in .c [if #incluir "-----.h" is in it] has the following content:
    Code:
    blabla
    bleble
    the output in the .txt file, where i will keep the copy of the lines,will be something like:
    Code:
    blabla
    
    bleble

    this is my program:

    Code:
    #include <stdio.h>
    #include <string.h>
    #define MAXLINE 1024
    int main(int argc, char * argv[])
    {
      int j,k;
      char *incluir="#incluir";
      char line[MAXLINE];
      char line2[MAXLINE];
      FILE *res;
      FILE *h;
      FILE *fp;
      fp=fopen(argv[1],"r");
      res=fopen(argv[2],"w+");
      printf(" My first argument was %s\n", argv[1]);
      printf(" My second argument was %s\n",argv[2]);
      
      if(fp==NULL) /* if it cant open */
        printf("File cant open %s\n",argv[1]); 
      else
        { /* if it can */
          printf("File %s successfully opened !!! \n",argv[1]); 
          
          
          while(fgets(line, MAXLINE , fp)) /* copies the first line */
    	{
    	  printf("1st while loop, line copied from argv[1]\n"); /* making sure it enters the loop */
    	  if(strstr(line,incluir)!= 0) /* looks for "#incluir" in the line */ 
    	    {
    	      printf("COOL it exists\n");
    	      
    	      /* in order to copy the name of the file i must first 
    		 know until where i will copy,
    	         the name is between '"' ( "--------.h" ) */
    	      j=0;
    	      while( line[j++]!='\"');
    	      /* now int j has the position of where 
    		 the first ' " ' is */
    	      
    	      
    	      /* the file *.c has in it -> #incluir "------.h" <-
    		 the first ' " ', occurs at the position j,
    		 but i only need the name, so all it is before
    		 i can shift to the left, therefor... */
    	      
    	      for(k=0; k<=MAXLINE-j; k++, j++)
    		line[k]=line[j];
    	      j=0;
    	      while( line[j++]!='\"');
    	      /* 2nd occurence of '"' */
    	      
    	      line[j-1]='\0';
    	      /* the element before the last one,
    		 should be '\0', in order to make it
    		 a string, but i also need to
    		 get rid of '"', so i placed '\0'
    		 before the '"'   */
    
    	      printf("%s \n", line);
    	      /* debugging purposes */
    	      h=fopen(line, "r");
    	      if(h!=NULL)
    		printf("file %s successfully opened\n", line);
    	      while( fgets(line2, MAXLINE, h))
    		{
    		  printf("%s\n",line2);
    		  fprintf(res,"%s\n",line2); /* write the line in the h file, to the res file */
    		  printf(" While loop working...\n");
    		}
    	    } 
    	  else
    	    {
    	      printf("%s\n", line); /* for debugging purposes */
    	      printf("%s\n", incluir);
    	      printf("OOPS it doesn't\n"); 
    	    }
    	}
        }
      return 0;
    }
    although i know the problem is in this loop
    Code:
    while( fgets(line2, MAXLINE, h))
    		{
    		  printf("%s\n",line2);
    		  fprintf(res,"%s\n",line2); /* write the line in the h file, to the res file */
    		  printf(" While loop working...\n");
    		}
    When i copy the last line, fgets doesnt copy '\n', and i need that, any advice on how to get over it?

  2. #2
    and the hat of wrongness Salem's Avatar
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    > When i copy the last line, fgets doesnt copy '\n', and i need that, any advice on how to get over it?
    It sounds more likely that your input file doesn't have a newline at the end of the last line.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
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  3. #3
    Registered User
    Join Date
    Apr 2004
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    13

    Red face

    *blushes*, i really am a noob at this, thanks for pointing that out.

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