help with structures

This is a discussion on help with structures within the C Programming forums, part of the General Programming Boards category; Hi, i'm trying to understand structures so i tried with this example: Code: #include <stdio.h> int main() { struct book ...

  1. #1
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    help with structures

    Hi, i'm trying to understand structures so i tried with this example:
    Code:
    #include <stdio.h>
    int main()
    {
    	struct book {
    		char name;
    		float price;
    		int pages;
    	};
    	struct book b1, b2, b3;
    	
    	printf("\nEnter names, prices, and number of pages of 3 books:\n");
    	scanf("%c %f %d", &b1.name, &b1.price, &b1.pages);
    	scanf("%c %f %d", &b2.name, &b2.price, &b2.pages);
    	scanf("%c %f %d", &b3.name, &b3.price, &b3.pages);
    	printf("\nAnd this is what you entered:\n");
    	printf("\n%c %f %d", b1.name, b1.price, b1.pages);
    	printf("\n%c %f %d", b2.name, b2.price, b2.pages);
    	printf("\n%c %f %d\n", b3.name, b3.price, b3.pages);
    	
    	return 0;
    }
    the output is wrong though, the program lets me input only the data for the first and second books but not for the third, heres what happens:
    Code:
    Enter names, prices, and number of pages of 3 books:
    a 234 234
    b 243 235
    
    And this is what you entered:
    
    a 234.000000 234
    
     0.000000 0
    b 243.000000 235
    can someone explain me why this happens? thanks!

  2. #2
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    scanf leaves the newline in the input buffer, so the second call to scanf will first see the newline character and decide it can't do anything. Then the third call to scanf gets the second line you entered.

  3. #3
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    You can modify your scanf() calls to handle the newline's that are left in the input buffer:
    Code:
        scanf("%c %f %d", &b1.name, &b1.price, &b1.pages);
        scanf("\n%c %f %d", &b2.name, &b2.price, &b2.pages);
        scanf("\n%c %f %d", &b3.name, &b3.price, &b3.pages);
    bit∙hub [bit-huhb] n. A source and destination for information.

  4. #4
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    Thanks, i really did think about it.. so the second scanf was receiving the newline character thats why it messed up

  5. #5
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    It'll mess up the second scanf because the %c specifier doesn't skip over whitespace.
    This means that b2.name will get the newline and other members of b2 will be zero.
    One way to get around this would be to convert all the %c specifiers to %s.

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