Another sscanf() question.

This is a discussion on Another sscanf() question. within the C Programming forums, part of the General Programming Boards category; Code: #include <stdio.h> void valid_buy(int *, char *, float *); int main() { int quantity = 0; char description[80]; float ...

  1. #1
    Registered User
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    Another sscanf() question.

    Code:
    #include <stdio.h>
    
    void valid_buy(int *, char *, float *);
    
    int main()
    {
        int quantity = 0;
        char description[80];
        float price = 0;
    
        valid_buy(&quantity, description, &price);
    
        printf("Quantity: %d\nDescription: %s\nPrice: %f\n", quantity, description, price);
    
        return 0;
    }
    
    void valid_buy(int *quantity, char *description, float *price)
    {
        char line[]= "1,blue car,2500.00";
    
        /* I know I'm ignoring the return value of sscanf() but it's just for now */
        sscanf(line, "%d, %49[^,], %f", &quantity, description, &price);
    }
    The string "blue car" gets assigned to variable description. However, int quantity and float price still have the value of 0, Why?

  2. #2
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    Code:
    void valid_buy(int *quantity, char *description, float *price)
    {
        char line[]= "1,blue car,2500.00";
    
        /* I know I'm ignoring the return value of sscanf() but it's just for now */
        sscanf(line, "%d, %49[^,], %f", &quantity, description, &price);
    }
    Note that quantity and price are already pointers. You don't need the address of the pointer. Try instead:
    Code:
    sscanf(line, "%d, %49[^,], %f", quantity, description, price);
    If I did your homework for you, then you might pass your class without learning how to write a program like this. Then you might graduate and get your degree without learning how to write a program like this. You might become a professional programmer without knowing how to write a program like this. Someday you might work on a project with me without knowing how to write a program like this. Then I would have to do you serious bodily harm. - Jack Klein

  3. #3
    Code Goddess Prelude's Avatar
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    quality and price are already pointers, you can safely remove the address-of operator:
    Code:
    sscanf(line, "%d, %49[^,], %f", quantity, description, price);
    My best code is written with the delete key.

  4. #4
    and the hat of wrongness Salem's Avatar
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    Now you know why "gcc -Wall" is a good idea.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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