Thread: error checking problem with scanf

  1. #1
    Learner Axel's Avatar
    Join Date
    Aug 2005

    error checking problem with scanf

    I have the following code:

    int main()
        FILE *fp;
        char name[25];
        char buff[BUFSIZ];
        float num;
            perror("File cannot be opened");
        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);
            printf("line cannot be printed\n");
        return 0;

    and test.txt:

    Elsewhere 22.65 11.95
    Overthere 55
    Sidknee 147 34

    Since "55" isn't a valid double, i don't want to print any of the records. What's happening now is:

    Sarah 22.65 11.95
    line cannot be printed
    Sandy 147.00 34.00

    Is there anyway when theres a int found to exit and print nothing but an error message?

  2. #2
    and the hat of int overfl Salem's Avatar
    Join Date
    Aug 2001
    The edge of the known universe
    Then read your 'double' into another string variable (like you do with name), then use say strtod() and perhaps strchr() to make sure it meets your rather exact definition of a double.
    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.

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