sscanf() examples?

This is a discussion on sscanf() examples? within the C Programming forums, part of the General Programming Boards category; I've tried reading around and i haven't had any luck getting sscanf to work with what i'm trying to do. ...

  1. #1
    Learner Axel's Avatar
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    sscanf() examples?

    I've tried reading around and i haven't had any luck getting sscanf to work with what i'm trying to do. Initially, i was using strtok to chop up some values that i need to store them into seperate variables in my link list. I was wondering if there are any simple examples for sscanf
    to save the following somewhere so i can store them into a linklist:

    Sarah 111.2

    I just want to be able to get a reference to "Sarah" and store it somewhere so i can pass it to my addtolist method. It's quiet easy hard coding it i.e. having a variable to store the name and total earnings but once i add more employees to the text file the old values are overwritten.

    Any help would be appreciated.

  2. #2
    Registered User ssharish2005's Avatar
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    well, here is an exmaple of sccanf fucntion
    Code:
    #include<stdio.h>
    
    int main()
    {
        char buff[20]={"Sarah 111.2"};
        char name[10];
        float num;
        
        sscanf(buff,"%s %f",name,&num);
        
        printf("%s %.2f",name,num);
        
        getchar();
    }
    /*myouput
    Sarah 111.20
    */
    hope this hepls
    ssharish2005

  3. #3
    and the hat of wrongness Salem's Avatar
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    Code:
    char name[BUFSIZ];
    double val;
    char buff[BUFSIZ] = "Sarah 111.2";   /* replace with calls to fgets() to read from a file/user */
    if ( sscanf (buff, "%s %lf", name, &val ) == 2 ) {
      /* valid data, do stuff */
    }
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  4. #4
    Learner Axel's Avatar
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    Thanks alot although theres a minor problem. Both solutions work fine for static text. I've basically done the same the same thing, but created a buffer dynamically depending on the text file inputted. if the text contains 'Sarah 111.2' it works fine. But if i add another line with a different name the second line is not printed

  5. #5
    Registered User ssharish2005's Avatar
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    well, you have to read line by line using a fgets function and use sscanf to get name and the number. the follwing code might help u

    Code:
    #include<stdio.h>
    
    int main()
    {
        FILE *fp;
        char name[25];
        char buff[BUFSIZ];
        float num;
        
        if((fp=fopen("test.txt","r"))==NULL)  
        {
            perror("File cannot be opened");
            getchar();
            exit(1);
        }
        
        while(fgets(buff,sizeof(buff),fp)!=NULL)  // read a single line from the file till i get EOF
        {
            if(sscanf(buff,"%s %f",name,&num)==2)  // getting the name and the number from the  buffer which was read from the file
            printf("%s %.1f\n",name,num);
            else
            printf("line cannot be printed\n");
        }
        
        getchar();
        return 0;
    }
    /* myoutput
    Sarah 111.2
    John 222.3
    Alan 333.4
    */
    and the test file test.txt
    Sarah 111.2
    John 222.3
    Alan 333.4

    ssharish2005

  6. #6
    Learner Axel's Avatar
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    ssharish, thanks alot. one problem though if i put sarah 11 in the text file it converts it to a double(11.0) is there anyway to get it to go to the "else" statement (ive tested with string etc it works fine, puts out an error as expected)

  7. #7
    Learner Axel's Avatar
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    never mind, i figured it out. But there's still one problem:

    Don 33.65 11.95
    Sarah 55
    Tom 122 34

    since the file doesn't have correct float variables (line 2, 3) is there anyway to send an error even though the first line is valid? At the moment as soon as it finds one it will print it and then the else statement comes into effect.

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