scanf() and doubles?

I am having an issue with the following program. This is just a simple program that calculates the surface area/volume of a cylinder. For some reason this executes JUST fine in CodeBlocks. Everything works exactly as it should and I get the correct values.

However, when I try to run it in the IDE that my professor forces us to use I always get 0 for values. If I change all the variables to int and use %d it will compile fine in both, but I lose accuracy. Double is required. Is %lf the correct scanf() function to use for doubles? I have tried many different things and I cannot get it to work properly in the IDE for my class.

Here is the following code:

Code:

#include <stdio.h>
#define PI 3.141593


double computation(double l, double r)
{
    if (2*r >= l)
    {
        printf("These dimensions do not define a valid tank");
    }
    else
    {
    double volCYL = (PI * r * r * l);
    double volSPH = (4.0/3.0 * PI * r * r * r);
    double surfCYL = (2 * PI * r * l);
    double surfSPH = (4 * PI * r * r);


    printf("\n");
    printf("A cylindrical tank of length %.3lf and radius %.3lf with inverted spherical\n", l,r);
    printf("caps has\n");
    printf("volume: %.3lf\n", volCYL-volSPH);
    printf("and\n");
    printf("surface area: %.3lf\n", surfCYL+surfSPH);
    printf("\n");
    printf("Program Termination.\n");
    }
    return 0;
}


double length = 0;
double radius = 0;




int main()
{
    printf("ACME Truck Company\n");
    printf("\n");
    printf("This program will calculate the volume and surface area of the x-11\n");
    printf("cylindrical tank\n");
    printf("Enter the length of the tank (feet)");
    scanf("%lf",&length);


    while (length < 10 || length > 20)
    {
        printf("Invalid value\n");
        printf("Please enter a value between 10 and 20:");
        scanf("%lf", &length);
        getchar();
    }


    printf("Enter the radius of the tank (feet)");
    scanf("%lf", &radius);


    while (radius < 3 || radius > 6)
    {
        printf("Invalid value\n");
        printf("Please enter a value between 3 and 6:");
        scanf("%lf", &radius);
        getchar();
    }


    computation(length,radius);
    return 0;
}

Any help would be much appreciated!

Originally Posted by Frankie15

I am having an issue with the following program. This is just a simple program that calculates the surface area/volume of a cylinder. For some reason this executes JUST fine in CodeBlocks. Everything works exactly as it should and I get the correct values.

However, when I try to run it in the IDE that my professor forces us to use I get garbage numbers. If I change all the variables to int and use %d it will compile fine in both, but I lose accuracy. Double is required. Is %lg the correct scanf() function to use for doubles? I have tried many different things and I cannot get it to work properly in the IDE for my class.

Yes, "%lg" is correct for doubles for scanf, but you only need "%g" for printf according to printf(3): formatted output conversion - Linux man page.

EDIT: If that doesn't fix it, tell us what compiler you're using with Code::Blocks that works, and what IDE/compiler you have to use for school.

Thank you SO much anduril.

Ok, I used %lg and %g (ignore code in updated original post. I thought it may have been lf instead of lg so I updated.)
Using %g instead of %lg worked PERFECTLY. Again, thank you!

%lg for scan and %g is working fine now to get whole number values, BUT I am having trouble getting it to display to three decimal places. Wouldn't you just type:

"%.3g"?

EDIT: It seems using %.3f will work for printing 3 decimal places. Is it acceptable to print an "lg" variable with "%f?

Yes, it's acceptable to use %f for your output. Actually, I almost always see %f used for floats/doubles, and rarely, if ever, see %g or %e, though to be fair, I don't write scientific code, so I don't need scientific notation. Read the link in my previous post carefully, particularly the parts for the "f,F" and "g,G" specifiers if you want all the details.

EDIT: and you're welcome.

Thanks for the link as well. I will use that to review for sure.

Thanks again for your help. Appreciate you taking the time to do so!