Binary File -> End of File

This is a discussion on Binary File -> End of File within the C Programming forums, part of the General Programming Boards category; The binary file output has one extra line then the original line. Is the EOF detected correctly or there is ...

  1. #1
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    Binary File -> End of File

    The binary file output has one extra line then the original line. Is the EOF detected correctly or there is a bug while writing the binary file?

    Can someone pl look the code and reason..

    Code:
    #include <stdio.h>
    #include<conio.h>
    
    int main()
    
    {
    
        int i,j;
    
        FILE *f,*fp;
    	double x[3];
    
        f=fopen("fm.bin","wb");
    	fp = fopen("fmout.txt","r");
    	
        if (!f)
    
            return 1;
    
    	if (!fp)
    
            return 1;
    
    	while(!feof(fp))
    	{
    		for(i=0;i<=2;i++)
    		{
    			fscanf(fp," %lf ",&x[i]);
    			fwrite(&x[i],sizeof(double),1,f); 
    			printf("  %lf ",x[i]);
    			
    		}
    		printf("\n");
    		
    	}
    	
        
    	fclose(f);
    	fclose(fp);
    	
    
    	printf("\n Reading Binary file...\n");
    	f = fopen("fm.bin","rb");
    
    	while(!feof(f)) 
    	{
    		printf("\n");
    		for(i=0;i<=2;i++)
    		{
    			fread(&x[i],sizeof(double),1,f);
    			printf(" %lf ",x[i]);
    		}
    		getch();
    	}
    
    	fclose(f);
    
    }
    Output:

    Contents of fmout.txt:
    Code:
    0.981649	   0.02342    0.1342
    Contents printed on screen from Binary file
    Code:
    0.981649	   0.02342    0.1342
    0.981649	   0.02342    0.1342
    Thanks!

  2. #2
    Yes, my avatar is stolen anonytmouse's Avatar
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  3. #3
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    Yup, makes sense! Thanks...

    Added this:

    Code:
    fread(&x[i],sizeof(double),1,f);
    if(feof(f)) break;

  4. #4
    ATH0 quzah's Avatar
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    Go back and read it again, because seem to have ignored the title of the FAQ, and I suspect the contents as well. Try again, staring with the title:

    Why it's bad to use feof() to control a loop

    Quzah.
    Hope is the first step on the road to disappointment.

  5. #5
    Frequently Quite Prolix dwks's Avatar
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    Hint: check the return value of fread().
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
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  6. #6
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    And you're also using the wrong format specifier to print a double. You might want to fix that after you're done rewriting your read loop.

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