having problems with updating records of one file to another file

This is a discussion on having problems with updating records of one file to another file within the C Programming forums, part of the General Programming Boards category; i am having problems of updating record present in one file and writing them onto another file in the same ...

  1. #1
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    having problems with updating records of one file to another file

    i am having problems of updating record present in one file and writing them onto another file in the same record format. it will write the input from command line onto incomingr.dat but not collectr.dat.no errors .
    the code is as follows
    Code:
    #include<stdio.h>
    #include<stdlib.h>
    //#include<conio.h>
    struct request
    {
    float percent_seq;
    char type_of_request[20];
    int request_size;
    };
    
    struct collectrequest
    {
    float percent_seq;
    char type_of_request[20];
    int request_size;
    };
    struct request r;
    int main()
    {
    FILE *fp;
    
    fp=fopen("INCOMINGR.DAT","w");
    if(fp==NULL)
    {
    printf("cannot open file");
    return 0;
    }
    
    printf("\n enter percent_seq,type_of_request and request_size");
    scanf("%f%s%d",&r.percent_seq,r.type_of_request,&r.request_size);
    fprintf(fp,"%f%s%d\n",r.percent_seq,r.type_of_request,r.request_size);
    fflush(stdin);
    insertcollectrequest(fp);
    
    
    fclose(fp);
    return 0;
    }
    int insertcollectrequest(FILE *fp)
    {
    FILE *fp2;
    struct collectrequest cr;
    fp2=fopen("COLLECTR.DAT","w+i");
    if(fp2==NULL)
    {
    printf("cannot open file");
    return 0;
    }
    while(fread(&r,sizeof(r),1,fp)==1)
    {
    fprintf(fp2,"%f%s%d\n",cr.percent_seq,cr.type_of_request,cr.request_size);
    }
    fclose(fp2);
    }

  2. #2
    spurious conceit MK27's Avatar
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    If you properly indent your code, it will be more readable, and more people will read it.

    "fflush(stdin)" results in undefined behavior according to the C standard, so until you get rid of that it cannot be eliminated as the potential source of your problem. I presume you are using it to get rid of characters left in the stdin stream buffer. There are better ways to deal with this that do not involve invoking undefined behavior.

    For example, write a function that reads a line of input into a local char buffer and extracts the data you want from that.
    C programming resources:
    GNU C Function and Macro Index -- glibc reference manual
    The C Book -- nice online learner guide
    Current ISO draft standard
    CCAN -- new CPAN like open source library repository
    3 (different) GNU debugger tutorials: #1 -- #2 -- #3
    cpwiki -- our wiki on sourceforge

  3. #3
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    You are reading your fp file in records and trying to write out text... is there some reason you need to do that?

    Also you are reading record r but printing to file from record cr ... I'm thinking you should make up your mind

    Pluse as already noted ... Some from of structured text formatting ... horizontal indentation, vertical white space, etc. is going to make it a lot --a huge lot-- easier to find this kind of stuff in your code. Take a look at how other people indent and separate their code... there's a reason for it.

  4. #4
    and the hat of wrongness Salem's Avatar
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    > fp2=fopen("COLLECTR.DAT","w+i");
    What does "i" mode do?
    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.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  5. #5
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    no it was printed by mistake the only w+ is the mode

  6. #6
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    Quote Originally Posted by Salem View Post
    > fp2=fopen("COLLECTR.DAT","w+i");
    What does "i" mode do?
    Create selfish code?

  7. #7
    and the hat of wrongness Salem's Avatar
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    > no it was printed by mistake the only w+ is the mode
    How can you print something by mistake, from doing a copy/paste from your code editor to the forum?

    Unless you're telling us this isn't your real code, and that you're just wasting everyone's time
    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.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  8. #8
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    the actual code is
    Code:
    #include<stdio.h>
    #include<stdlib.h>
    //#include<conio.h>
    /*this structure is for taking a request from command line*/
    struct request
    {
    float percent_seq;
    char type_of_request[20];
    int request_size;
    };
    /*this struct is for having that incoming request appended onto it until a condition is reached*/
    struct collectrequest
    {
    float percent_seq;
    char type_of_request[20];
    int request_size;
    };
    struct request cr;
    int main()
    {
    FILE *fp;
    
    fp=fopen("INCOMINGR.DAT","w");
    if(fp==NULL)
    {
    printf("cannot open file");
    return 0;
    }
    
    printf("\n enter percent_seq,type_of_request and request_size");
    scanf("%f%s%d",&r.percent_seq,r.type_of_request,&r.request_size);
    fprintf(fp,"%f%s%d\n",r.percent_seq,r.type_of_request,r.request_size);
    fflush(stdin);
    insertcollectrequest(fp);
    
    
    fclose(fp);
    return 0;
    }
    
    int insertcollectrequest(FILE *fp)
    {
    FILE *fp2;
    struct collectrequest cr;
    fp2=fopen("COLLECTR.DAT","w+");
    if(fp2==NULL)
    {
    printf("cannot open file");
    return 0;
    }
     while((fscanf(fp,"%f%s%d",&r.percent_seq,r.type_of_request,&r.request_size))!=EOF)
    {
    fprintf(fp2,"%f%s%d\n",r.percent_seq,r.type_of_request,r.request_size);
    }
    fclose(fp2);
    }

  9. #9
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    i want to read records from file in record format as well as write on to other file in record format.

  10. #10
    and the Hat of Guessing tabstop's Avatar
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    You keep using a variable called "r", but you don't have one. How are you even compiling this code?

    You also don't prototype your function, which means that may only work by the grace of your compiler, plus you haven't gotten rid of fflush(stdin) yet.

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