stuck with first c program

[toku1991]

Hey people,
i was playing around with my first c program and i have a strange thing happening
when output is 0.001 the value is 1000 nOhm but it should be 100mOhm

// calculate resistance and print out how much omh it is
   case 1:
            printf("what is your Voltage?\n");
            scanf("%Lf", &volt);
            printf("what is your Amperage?\n");
            scanf("%Lf", &ampere);
            output = volt / ampere;
            if (output >= 0.0000000001 && output < 0.000001) {
                printf("%0.0Lf %s\n", output * 1e6, "nOhm"); // Convert to nano
                printf("%0.9Lf %s\n", output, "Ohm"); // Display as is
            }
            if (output >= 0.000001 && output < 0.001) {
                printf("%0.0Lf %s\n", output * 1e6, "uOhm"); // Convert to micro
                printf("%0.9Lf %s\n", output, "Ohm"); // Display as is

            }
            if (output >= 0.001 && output < 1 ) {
                printf("%0.0Lf %s\n", output * 1e3, "mOhm"); // Convert to mili
                printf("%0.9Lf %s\n", output, "Ohm"); // Display as is
            }
            if (output > 1) {
                printf("%0.0Lf Ohm\n", output);
            }

            break;

 

[EkBass]

Dividing with floats does not always produce accurate results. This is because at some point the division is rounded due the amount of decimals. I cant explain it better in english.

Next code is not tested, but i think it gets you atleast closer to what you need. Hope it help.

#include <stdio.h>
#include <float.h>

int main() {
    double volt, ampere, output;
    int rounding_mode;

    // calculate resistance and print out Ohm
    printf("What is your voltages? ");
    scanf("%lf", &volt);
    printf("What is your ampers? ");
    scanf("%lf", &ampere);
    output = volt / ampere;

    // set the rounding mode to as "nearest"
    rounding_mode = fesetround(FE_TO_NEAREST);

    // convert to Ohm
    if (output >= 0.0000000001 && output < 0.000001) {
        printf("%0.0lf nOhm\n", output * 1e6);
    } else if (output >= 0.000001 && output < 0.001) {
        printf("%0.0lf uOhm\n", output * 1e6);
    } else if (output >= 0.001 &&