Split string in sequential file to add a tabstop between the strings...

This is a discussion on Split string in sequential file to add a tabstop between the strings... within the C Programming forums, part of the General Programming Boards category; Hey everyone, I have the following code and trying to figure out a way to split the string, "Brown 3.75, ...

  1. #1
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    Split string in sequential file to add a tabstop between the strings...

    Hey everyone, I have the following code and trying to figure out a way to split the string, "Brown 3.75, Jones 4.00, etc. and then add a tabstop between them for printing. Is there a simple command or way to do this? Thanks in advance!
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #define N 100
    
    int main()
    {
        FILE *fP;
        char str[N], *c;
    
    
        if ((fP = fopen("names.dat", "r")) == NULL)
        {
            printf("%s not opened", "names.dat");
            exit(EXIT_FAILURE);
        }
        do {
            c = fgets(str, N ,fP);
            if (c != NULL)
    
                printf("%s\n", str);
            }
        while (c != NULL);
    
        fclose(fP);
    
        return 0;
    
    }

  2. #2
    Gawking at stupidity
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    You could use strchr():
    Code:
    char *column2 = strchr(str, ' ');
    if(column2)
      *column2++ = '\0';
    else
      column2 = str + strlen(str);
    printf("%s\t%s\n", str, column2);
    If you understand what you're doing, you're not learning anything.

  3. #3
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    *scanf with formatspecifier %s will split for you:
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #define N 100
    
    int main()
    {
        FILE *fP;
        char str[N], *c;
    
    
        if ((fP = fopen("names.dat", "r")) == NULL)
        {
            printf("%s not opened", "names.dat");
            exit(EXIT_FAILURE);
        }
    
        while( 1==fscanf(fP,"%99s",str) )
          printf("%s\t",str);
    
        fclose(fP);
    
        return 0;
    }

  4. #4
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    Quote Originally Posted by BillyTKid View Post
    *scanf with formatspecifier %s will split for you:
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #define N 100
    
    int main()
    {
        FILE *fP;
        char str[N], *c;
    
    
        if ((fP = fopen("names.dat", "r")) == NULL)
        {
            printf("%s not opened", "names.dat");
            exit(EXIT_FAILURE);
        }
    
        while( 1==fscanf(fP,"%99s",str) )
          printf("%s\t",str);
    
        fclose(fP);
    
        return 0;
    }
    Thanks, but I have to use fgets. That was my first thought as well.

  5. #5
    a_capitalist_story
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    If you have to use fgets, then use sscanf on the string returned!

  6. #6
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    Quote Originally Posted by rags_to_riches View Post
    If you have to use fgets, then use sscanf on the string returned!
    Now I am getting just one line of my .dat file and it happens to be the last one. Did I miss something?

  7. #7
    and the Hat of Guessing tabstop's Avatar
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    You're probably overwriting each time. Either print it out inside the loop, or save it somewhere.

  8. #8
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    Quote Originally Posted by BillyTKid View Post
    *scanf with formatspecifier %s will split for you:
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #define N 100
    
    int main()
    {
        FILE *fP;
        char str[N], *c;
    
    
        if ((fP = fopen("names.dat", "r")) == NULL)
        {
            printf("%s not opened", "names.dat");
            exit(EXIT_FAILURE);
        }
    
        while( 1==fscanf(fP,"%99s",str) )
          printf("%s\t",str);
    
        fclose(fP);
    
        return 0;
    }
    I really like what you did here, but can you tell me how I would get this print out?
    Brown 3.75
    Jones 4.00

    Basically I need to have a "name <tab> GPA" then a new line with the same.

  9. #9
    Gawking at stupidity
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    Dude, the strchr() solution is faster/cleaner. If you omit the error checking just do this:
    Code:
    char *gpa = strchr(str, ' ');
    *gpa++ = '\0';
    printf("%s\t%s\n", str, gpa);
    Is there a reason you don't want to use it?
    If you understand what you're doing, you're not learning anything.

  10. #10
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    Quote Originally Posted by itsme86 View Post
    Dude, the strchr() solution is faster/cleaner. If you omit the error checking just do this:
    Code:
    char *gpa = strchr(str, ' ');
    *gpa++ = '\0';
    printf("%s\t%s\n", str, gpa);
    Is there a reason you don't want to use it?
    Not at all, I am trying that as we speak. Just trying to understand it that is all. I really appreciate your help. Thank you!

  11. #11
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    Quote Originally Posted by csharp100 View Post
    Not at all, I am trying that as we speak. Just trying to understand it that is all. I really appreciate your help. Thank you!
    Works good till a point, it prints out the output but then it stops working or other words the program does not exit on its own. I get a windows error and I am using codeblocks with the gcc compiler. Just Tried it on our unix system and I am getting a segmentation fault. Here is my code.
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #define N 100
    
    int main()
    {
        FILE *fP;
        char str[N], *c;
        char *gpa = strchr(str, ' ');
    
    
        if ((fP = fopen("names.dat", "r")) == NULL)
        {
            printf("%s not opened", "names.dat");
            exit(EXIT_FAILURE);
        }
        do {
            c = fgets(str, N ,fP);
            char *gpa = strchr(str, ' ');
            *gpa++ = '\0';
            printf("%s\t%s\n", str, gpa);
    
    
    
    
            }
        while (c != NULL);
    
        fclose(fP);
    
        return 0;
    
    }
    Last edited by csharp100; 12-14-2010 at 04:17 PM.

  12. #12
    and the Hat of Guessing tabstop's Avatar
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    When c is NULL you need to stop RIGHT NOW, not "after this loop is finished".

  13. #13
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    Quote Originally Posted by tabstop View Post
    When c is NULL you need to stop RIGHT NOW, not "after this loop is finished".
    Could you be a bit more specific? I placed an if statement within the do/while loop after the print statement:
    Code:
    if (c = NULL)
    break:
    What it did was only print out one line and tat was the first line of my .dat file.

  14. #14
    Registered User whiteflags's Avatar
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    Assignment is not equality:

    if(c == NULL) /* is it NULL? */

    if(c = NULL) /* assign NULL to C */

    Normally an IDE would warn if you use assignment in a boolean context. Turn up your warning level!

  15. #15
    Registered User
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    Quote Originally Posted by whiteflags View Post
    Assignment is not equality:

    if(c == NULL) /* is it NULL? */

    if(c = NULL) /* assign NULL to C */

    Normally an IDE would warn if you use assignment in a boolean context. Turn up your warning level!
    Dang! Another segmentation fault. The latest code:
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #define N 100
    
    int main()
    {
        FILE *fP;
        char str[N], *c;
        char *gpa = strchr(str, ' ');
    
    
        if ((fP = fopen("names.dat", "r")) == NULL)
        {
            printf("%s not opened", "names.dat");
            exit(EXIT_FAILURE);
        }
        do {
            c = fgets(str, N ,fP);
            char *gpa = strchr(str, ' ');
            *gpa++ = '\0';
            printf("%s\t%s\n", str, gpa);
            if (c == NULL)
            break;
    
    
    
            }
        while (c != NULL);
    
        fclose(fP);
    
        return 0;
    
    }

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