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Assertion Failure?

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Assertion Failure?

 
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  #1
Apr 8th, 2007
I'm trying to read from a text file. Pretty simple, right? I guess not. It gives me this error message:

Debug Assertion Failed!

Program: F:\Debug\lab1431.exe
File: fscanf.c

Expression: stream != NULL

For information on how your program can cause assertion failure, see the Visual C++ documentation on asserts.


C++ Syntax (Toggle Plain Text) 
  1. #include <stdio.h>
  2. #define FILENAME "F:/Debug/lab14data.txt"
  3.  
  4. int main(void)
  5. {
  6. 	int num_data_pts = 0, fday, day = 1;
  7. 	double ffahr, max, min;
  8. 	FILE *temp_each_day;
  9.  
  10. 	temp_each_day = fopen(FILENAME, "r");
  11. 	if (temp_each_day = NULL)
  12. 		printf("Error opening input file. \n");
  13. 	else
  14. 	{
  15. 		while (fscanf(temp_each_day,"%i %lf", &fday, &ffahr) == 2)
  16. 		{
  17. 			num_data_pts++;
  18. 			day++;
  19.  
  20. 			printf("      Day           Fahrenheit         Celsius");
  21. 			printf("%4i %7lf %7lf", fday, ffahr, (ffahr + 32) / 1.8);
  22.  
  23. 			if (num_data_pts == 1)
  24. 				max = min = ffahr;
  25. 			else if (ffahr > max)
  26. 				max = ffahr;
  27. 			else if (ffahr < min)
  28. 				min = ffahr;
  29. 		}
  30.         }
  31.  
  32. 	return 0;
  33. }
(program is unfinished, but still should work).

Why is it giving me this?
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Re: Assertion Failure?

 
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  #2
Apr 8th, 2007
close the file: fclose
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Re: Assertion Failure?

 
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  #3
Apr 8th, 2007
I just did that and it still comes up. I think it has to do with the opening of the file because if I remove the fscanf line, the error message doesn't come up.
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Re: Assertion Failure?

 
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  #4
Apr 8th, 2007 
if (temp_each_day = NULL)
        printf("Error opening input file. \n");
The = in the above code should be replaced by == if what you want to do is comparision.
Last edited by ~s.o.s~; Apr 8th, 2007 at 4:01 pm.
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Re: Assertion Failure?

 
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  #5
Apr 8th, 2007
since the debud assertion that fails is:
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Debug Assertion Failed!
Program: F:\Debug\lab1431.exe
File: fscanf.c
Expression: stream != NULL
the error is that at a place where the
stream was expected to be NULL, it is not NULL. stream (in the FILE structure)
would be NULL after the file has been closed.
remember that fscanf can corrupt memory if your format specifiers are incorrect.
Last edited by vijayan121; Apr 8th, 2007 at 4:06 pm. Reason: formatting
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Re: Assertion Failure?

 
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  #6
Apr 8th, 2007
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Originally Posted by ~s.o.s~ View Post 
if (temp_each_day = NULL)
        printf("Error opening input file. \n");
The = in the above code should be replaced by == if what you want to do is comparision.
I am an idiot. THANK YOU.
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Re: Assertion Failure?

 
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  #7
Apr 8th, 2007
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Originally Posted by ~s.o.s~ View Post 
if (temp_each_day = NULL)
        printf("Error opening input file. \n");
The = in the above code should be replaced by == if what you want to do is comparision.
that is clearly the error. once you assign NULL to temp_each_day,
a. the if block will not execute.
b. fclose(NULL) will assert and an assertion wil fail on exit if fclose is not called.
Last edited by vijayan121; Apr 8th, 2007 at 4:11 pm. Reason: format
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Re: Assertion Failure?

 
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  #8
Apr 8th, 2007
Programming brings to worst out of us...

You are welcome.
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Re: Assertion Failure?

 
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  #9
Apr 8th, 2007
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Originally Posted by shmay View Post
Why is it giving me this?
C++ Syntax (Toggle Plain Text) 
  1. if (temp_each_day = NULL)
the compiler would have given a warning for this.
tip: set the warning level of the compiler to the highest available, and pay attention to the warnings.
you would save yourself a great deal of effort and time.
Last edited by vijayan121; Apr 8th, 2007 at 4:21 pm. Reason: format
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