Thread: Can anyone explain what I'm doing wrong? Runs but doesn't let the user input

I'm new to programming and very confused.

Code:

#include <stdio.h>


#define INCHES_IN_CUBIC_FOOT 1728


int main () {
    double length_in_inches; 
    double width_in_inches;
    double height_in_inches;
    
    printf("Length: ");
    scanf("%lf", &length_in_inches);
    
    printf("Width: ");
    scanf("%.2lf", &width_in_inches);
    
    printf("Height: ");
    scanf("%d", &height_in_inches);
    
    float num_1 = length_in_inches * width_in_inches* height_in_inches;
    printf("Volume in Cubic Inches: %.2lf", num_1);
    
    float num_2 = (length_in_inches * width_in_inches*height_in_inches) /INCHES_IN_CUBIC_FOOT;
    printf("Volume in Cubic feet:%.2lf", num_2);


    return 0;
    }

If it lets you enter the length but not width it is probably because of those "extra" characters in your scanf() format string.

If you're compiler was properly configured it should be able to warn you about these issues:

main.c||In function ‘main’:|
main.c|16|warning: unknown conversion type character ‘.’ in format [-Wformat=]|
main.c|16|warning: too many arguments for format [-Wformat-extra-args]|
main.c|19|warning: format ‘%d’ expects argument of type ‘int *’, but argument 2 has type ‘double *’ [-Wformat=]|
||=== Build finished: 0 error(s), 3 warning(s) (0 minute(s), 1 second(s)) ===|

Jim

C

or maybe he is using C syntax and compiling C++. I know this very well.

Ok lad, I think I have your code but is still in C syntax:

There were two mistakes: the scanf of height had a format %d while with double you should put %lf. In scanf please don't put any precision, only to read the result with printf, so I removed the .2 in width scanf. I also added some \n in printf to end line so the output is prettier.

Code:

#include <stdio.h>

#define INCHES_IN_CUBIC_FOOT 1728

    int main () {
    double length_in_inches;
    double width_in_inches;
    double height_in_inches;

    printf("Length: ");
    scanf("%lf", &length_in_inches);

    printf("Width: ");
    scanf("%lf", &width_in_inches);

    printf("Height: ");
    scanf("%lf", &height_in_inches);

    float num_1 = length_in_inches * width_in_inches* height_in_inches;
    printf("Volume in Cubic Inches: %.2lf\n", num_1);

    float num_2 = (length_in_inches * width_in_inches*height_in_inches) /INCHES_IN_CUBIC_FOOT;
    printf("Volume in Cubic feet:%.2lf\n", num_2);

    return 0;
    }