Thread: If-else loop issues

Hi, I am a newbie to C, and I am having issues while running the following code:

Code:

#include<stdio.h>
#include <math.h>
#include <stdlib.h>
#define rho_l 1000


int main()
{
    float cw,eta,rho_m,rho_s,D_i;
    float Re_b,tao_0,He,V;
    float fnl,a,b,fnt;
    float fn,m,fd,Pd_l;
    char ch,ch1;


    printf("\nIs the slurry density known?(Y/N) ");
    scanf("%c",&ch);


    if (ch == 'Y' || ch == 'y')
    {
        printf("\nEnter slurry density: ");
        scanf("%f",&rho_m);
    }
    else //if (ch == 'N' || ch == 'n')
    {
        
        printf("\nIs solid density known?(Y/N) ");
        scanf("%c",&ch1);
        printf("%c is value of ch",ch1);
        if (ch1 == 'Y' || ch1 == 'y')
        {
            printf("\nEnter solid density: ");
            scanf("%f",&rho_s);
            printf("\nInput Slurry Concentration: ");
            scanf("%f",&cw);
            rho_m = 100/((cw/rho_s)+((100-cw)/rho_l) );            //Calculate Slurry density
        }
        else if (ch1 == 'N' || ch1 == 'n')
        {
            printf("\nInsufficient data: ");
            exit(0);
        }
        else
        {
            printf("\nInvalid Input!");
            exit(0);
        }
    }
    else
    {
        printf("\nInvalid Input!");
        exit(0);
    }




    printf("\nInput Pipe Diameter: ");
    scanf("%f",&D_i);


    printf("Input flow velocity: ");
    scanf("%f",&V);


    printf("Input yield stress: ");
    scanf("%f",&tao_0);


    printf("Input Slurry Viscosity: ");
    scanf("%f",&eta);


    // Calculate Reynold's number for BinghamPlastic flow
    Re_b = (D_i*V*rho_m)/eta;
    printf("\n %f is the Reynold's number",Re_b);


    // Calculate Hedstrom number
    He = (pow(D_i,2.0)*rho_m*tao_0)/pow(eta,2.0);
    printf("\n %f is the Hedstrom's number",He);


    //Calculate friction factor in laminar regime
    fnl = (16/Re_b)*(1 + Re_b/(6*He));
    printf("\n %f is the laminar friction factor",fnl);


    //Calcualte friction factor in turbulent regime
    a = -1.47*(1+0.416*exp(-2.9*pow(10,-5)*He));
    b = -0.193;
    fnt = pow(10,a)*pow(Re_b,b);
    printf("\n %f is the turbulent friction factor",fnt);
    printf("\n %f is a",a);


    //Calcualte overall Fanning friction factor
    m = 1.7 + 40000/Re_b;
    fn = pow((pow(fnl,m)+pow(fnt,m)),1/m);
    printf("\n %f is m",m);
    printf("\n %f is the overall friction factor",fn);


    //Calcualte Darcy friction factor
    fd = 4*fn;
    printf("\n %f is the Darcy friction factor",fd);


    //Calculate pressure drop per unit length
    Pd_l = (rho_m*fd*pow(V,2.0))/(2*D_i);


    printf("\n %f is the pressure drop in Pa/m",Pd_l );
    return 0;
    getch();
}

When I chose 'Y' for the first question

Code:

Is the slurry density known?(Y/N)

then the program works well, but when I chose 'N' then the program prints

Code:

Is solid density known?(Y/N)

and then

Code:

 Invalid Input!

. It does not take any input from me in that case.

The code does not go into the second if-else loop. How do I solve this problem?
Thanks...

Thank you, this helped