Any better & efficient alternative to this C prg.

This is a discussion on Any better & efficient alternative to this C prg. within the C Programming forums, part of the General Programming Boards category; I have wrote the following C prg. to display random record contents from text file 'pix.db' (free format). It generates ...

  1. #1
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    Any better & efficient alternative to this C prg.

    I have wrote the following C prg. to display random record contents from text file 'pix.db' (free format). It generates random num from 1 to 10 and then fetches corr. record from 'pix.db'

    File pix.db format: (note '|' is my field sepator)
    ID|pix file|pic name

    for example:
    1|pix1.gif|pix1name
    2|pix2.gif|pix2name
    3|pix3.gif|pix3name
    ;;
    ;;
    ;;
    10|pix10.gif|pix10name

    Here is the 'C' code which I consider best but I don't know how efficient it is..... Does anyone know better & efficeint code for the following code....I am not 'C' guru....but I know this forum has some finest 'C' experts....hope they help me out here....Thanks in advance.

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <time.h>

    void file_process(char *flname, int rnd_num, char *cdata);
    void err_default(void);

    int main(void)
    {
    FILE *rd_fp;
    char *temp, *pch, *pname, *pix, got_err='N';
    int pnum = 10; /* for random no. any record between 1..10 */

    temp = (char *) malloc( sizeof(char) * 150);
    pch = (char *) malloc( sizeof(char) * 150);

    /* calling function passing 'pnum' */
    file_process("pix.db", pnum, temp);

    /* split the record */
    strcpy(pch, strtok(temp, "|"));
    if ( (pix = strdup(pch)) == NULL) got_err='Y';
    strcpy(pch, strtok (NULL, "|"));
    if ( (pname = strdup(pch)) == NULL) got_err='Y';

    if(got_err == 'Y') print_error(); /* if error show default pix */

    /* display content */
    printf ("%s = %s", pix, pname);

    free(temp); free(pch);
    free(pix); free(pname);

    return(0);
    }

    void file_process(char *flname, int rnd_num, char *cdata)
    {
    FILE *fp;
    char recflag = 'N';
    int rec_number, rnd_number;
    time_t t;

    /* generate random number */
    srand((unsigned) time(&t));
    rnd_number = rand() % rnd_num+1;

    /* now get the corr. record */
    if ((fp = fopen(flname, "r")) == NULL) print_error();
    fscanf(fp, "%d", &rec_number);

    while( !feof(fp))
    {
    fgets(cdata, 150, fp);
    if(rec_number == rnd_number)
    {
    recflag = 'Y';
    break;
    }
    fscanf(fp, "%d", &rec_number);
    }
    fclose(fp);
    if(recflag == 'N') err_default();
    }

    void print_error(void)
    {
    printf ("ERROR - NO REC FOUND \n");
    exit(1);
    }

  2. #2
    ATH0 quzah's Avatar
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    Yes, there's a much better way to do this. Use binary files. Use structures. Use fread. Use fseek.

    Fixed size records are your friend.

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

  3. #3
    Unleashed
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    > Fixed size records are your friend.
    Code tags as well.
    The world is waiting. I must leave you now.

  4. #4
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    Post

    I have never used binary file....is there some good tutorial on the web where I can see some examples.......I appreciate your help.....My problem is I have a '|' delimiter in my database so I have no idea how to use fread and fseek functions.......
    can you help me out with some sample coding. Thanks in advance.

  5. #5
    and the hat of wrongness Salem's Avatar
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    > Fixed size records are your friend
    Except that the original post said free format

    Too much malloc and free where none is really required.

    And you use the dreaded feof()

    You also call fgets() and fscanf() to read the file, this is sure to lead to problems

  6. #6
    ATH0 quzah's Avatar
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    Originally posted by Salem
    > Fixed size records are your friend
    Except that the original post said free format

    Too much malloc and free where none is really required.

    And you use the dreaded feof()

    You also call fgets() and fscanf() to read the file, this is sure to lead to problems
    Free format meaning what exactly? He asked for a more efficient way of doing it. Fixed size records are the answer. If you really want to use a text file, you can, it's just not as efficient as fixed size.

    Besides, this isn't really a "free format" anyway. The records are a fixed format. They just have varying lengths of strings. "Free format" sounds like you can have any arbitrary data in there, or any number of a given 'variable' in it. Example:
    Code:
    RECORD record1
    integer 1000
    string My name is BillyBobJimJack.
    integer 3420
    float 3.5
    string Hello world
    END
    
    RECORD record2
    string Use code tags.
    string Read the FAQ.
    string Stop asking how to clear the screen.
    string Stop using 'void main'.
    END
    The parser in this case strips off the first word to see what the following will be. Then it reads to the end of the line. (Alternately, you could specify a delimit so strings could span multiple lines.)

    The information would be treed or stored in a list of some form.
    That'd be what I consider a 'free format'.

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

  7. #7
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    So what is the solution?

    Can someone fix my code OR give me alternative solution for the above program. Acc.to Salem(moderator) my code has too many problems like he mentioned with feof and fscanf... etc. What would you suggest Salem if you were asked to find solution for
    .....can you modify my code and give me correct one that you think.
    I have posted same problem in other forumsbut no one could able to find better solution. Hope you or other would throw some light on.....

    Thanks in advance. Appreciated.

  8. #8
    ATH0 quzah's Avatar
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    1) Use a buffer to read into instead of calling malloc/free for simple text reads. Once you actually have valid data, then malloc for your strings if you need to.

    2) Test the return value of your file read functions instead of using feof.

    Those are the first improvements I'd make. I am not going to do all your work for you, but with the above, you should be able to take it from there.

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

  9. #9
    and the hat of wrongness Salem's Avatar
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    Code:
    #include <stdio.h> 
    #include <stdlib.h> 
    #include <string.h> 
    #include <time.h>
    
    int main() { 
        char buff[BUFSIZ];
        FILE *fp;
        int  i, rec;
    
        srand( time(NULL) );
        rec = rand() % 10 + 1;
    
        fp = fopen("sample.txt","r");
        for ( i = 0 ; i < 10 ; i++ ) {
            int n;
            fgets(buff,BUFSIZ,fp);
            if ( sscanf( buff, "%d", &n ) == 1 && n == rec ) {
                char *filename, *filedesc, *p;
                p = strtok( buff, "|" );
                filename = strtok( NULL, "|" );
                filedesc = strtok( NULL, "|" );
                printf( "%s %s\n", filename, filedesc );
                break;
            }
        }
        fclose( fp );
    
        return 0; 
    }

  10. #10
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    Unhappy Couple of concern red your code?

    Hi Salem,
    Thanks for the alternative code ......looks clean and shorter than mine. BUT I have couple of concerns regd. the code they are:

    1) char buff[BUFSIZ]
    what is BUFSIZ and its size, don't you need to define it somewhere.

    2) int n;
    why did you defined it inside for loop......any specific reason.

    Appreciated. Once again thanks a million.

    perlguy.

  11. #11
    End Of Line Hammer's Avatar
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    Re: Couple of concern red your code?

    1) char buff[BUFSIZ]
    what is BUFSIZ and its size, don't you need to define it somewhere.
    Yep, it's defined in stdio.h, so don't worry.
    2) int n;
    why did you defined it inside for loop......any specific reason.
    That way the variable is only visible within the loop, and not within the rest of the function. This is the same for most variables created within braces.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

  12. #12
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    Question One last question....

    Thanks for propmt reply....this forum rocks....

    1) should I free memory used by *filename, *filedesc, *p variables or not? or is it done by system automatically when prg. exits...

    2) Is there any software to test performance of this prg.?
    for example: In perl/cgi we have some test tools that tells how many request perl/cgi prg. can handle at a time......

    let me know if any such tools fo C prg.

    regards
    perlguy.

  13. #13
    End Of Line Hammer's Avatar
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    Re: One last question....

    1) should I free memory used by *filename, *filedesc, *p variables or not? or is it done by system automatically when prg. exits...

    2) Is there any software to test performance of this prg.?
    for example: In perl/cgi we have some test tools that tells how many request perl/cgi prg. can handle at a time......
    1 - No you don't. The memory is owned by the buff variable.

    2 - Dunno! But you could write your own timer functions to encapsulate your code.
    When all else fails, read the instructions.
    If you're posting code, use code tags: [code] /* insert code here */ [/code]

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