Nothing is written to file

This is a discussion on Nothing is written to file within the C Programming forums, part of the General Programming Boards category; Thanks for your help earlier today! Here's another: newcalib.cal is empty after execution. Code: /* Program DIVIDE */ #include <stdio.h> ...

  1. #1
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    Nothing is written to file

    Thanks for your help earlier today!

    Here's another: newcalib.cal is empty after execution.

    Code:
    /* Program DIVIDE */
    
    #include <stdio.h>
    
    FILE* one;
    FILE* two;
    FILE* three;
    FILE* four;
    
    int main(void){
    
      float raw;
      float data;
      float delta;
      int dud;
    
      one = fopen("my113a_8_00.avg", "r");
      two = fopen("my113a_8_00C.dat", "r");
      three = fopen("differentials.dat", "r");
      four = fopen("newcalib.cal", "w");
    
      while(!EOF){
        fscanf(one,"%f", &raw);
        fscanf(two,"%f", &data);
        fscanf(three,"%d %f", &dud, &delta);
    
        printf("%f\n", delta);
        fprintf(four,"%f", raw/(delta+data));
      }
    
      fclose(one);
      fclose(two);
      fclose(three);
      fclose(four);
    }

  2. #2
    Registered User whiteflags's Avatar
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    Rather than exercizing proper loop control, you chose to just negate EOF outright. Well, EOF is a negative integer. So what do we end up with...
    Code:
    while( 0 ) {
       /* everything else */
    }
    No loop, no reading the files, no writing to files.

    > one = fopen("my113a_8_00.avg", "r");
    > two = fopen("my113a_8_00C.dat", "r");
    > three = fopen("differentials.dat", "r");
    > four = fopen("newcalib.cal", "w");

    Another significant problem is that you didn't make sure all of these FILE pointers were valid after the attempt to open a stream. If fopen didn't work, you don't know about it.

  3. #3
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    Quote Originally Posted by citizen View Post
    Rather than exercizing proper loop control


    Another significant problem is that you didn't make sure all of these FILE pointers were valid after the attempt to open a stream. If fopen didn't work, you don't know about it.
    if(!one)
    printf("Cannot open file");

    This should do..But still I wonder how you can open a stream to file without #include <fstream>
    Last edited by Sober; 05-04-2007 at 10:09 AM.

  4. #4
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by Sober View Post
    This should do..But still I wonder how you can open a stream to file without #include <fstream>
    What are you talking about? This is C...

  5. #5
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by slippy View Post
    Code:
    fprintf(four,"%f", raw/(delta+data));
    Other people told you the real problem. But you need to also put a "\n" at the end of this fprintf() string. Otherwise all your output is going to be jammed together into one very long line.

  6. #6
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    Other people told you the real problem. But you need to also put a "\n" at the end of this fprintf() string. Otherwise all your output is going to be jammed together into one very long line.
    Yeah, I chaged the loop expression and added the `\n' earlier:

    Code:
    while(EOF != fscanf(three, "%d %f", &dud, &delta)){
    
    /* There's probably still room for improvement.... */
    
    }

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