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Calculations in a for loop not working properly

Maniak47 (1)
Hi everyone,
I'm a total beginner to c++ and I am having a bit of trouble with calculations within a for statement the goal of the program is to calculate the stresses in a truss system based on the values inputted by the user. I used multiple for loops so that the user can input all the required data for the table and a for loop to calculate the values and output them in the format I want. Problem is the first iteration of the calculations doesn't work properly while the second and the third do. Even though its probably something simple I can't seem to figure it out, if anyone could point me in the right direction it would be much appreciated. 
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//
//
//
//

#include <iostream.h>

#include <iomanip.h>

#include <math.h>

#include <stdio.h>

int main()
{
    float const PI=3.141519;
    int run=1, x=0,row=1;
    float force_p[2], theta_p[2], theta_a[2], theta_b[2],theta_ar[2];
    float theta_br[2], theta_pr[2],force_a[2], force_b[2], force_px[2];
    float force_py[2], D[2];    
    while(run==1)
    {
                 //Setting IOS parameters
                 
                 cout<<setiosflags(ios::fixed)
                 <<setiosflags(ios::showpoint)
                 <<setprecision(2);
                 
                 
                 //Variable input
                                       
                 for(x;x<=2;x++)
                 {
                              cout<<"\n Row = "<<row<<"\n";    
                              cout<<"\nInput Force (P)\n";
                              cin>>force_p[x];
                              cout<<"\nInput angle of P with respect to the positive x-axis\n";
                              cin>>theta_p[x];
                              cout<<"\nInput angle of truss A to the positive x-axis\n";
                              cin>>theta_a[x];
                              cout<<"\nInput angle of truss B to the positive x-axis\n";
                              cin>>theta_b[x];
                              row++;



                 //Mass conversion of theta degrees into radians

                     theta_ar[x]=theta_a[x]*PI/180;
                     theta_br[x]=theta_b[x]*PI/180;
                     theta_pr[x]=theta_p[x]*PI/180;

                 
                 //Number Crunching

                     D[x]=sin(theta_b[x]-theta_a[x]);                  
                     force_px[x]=force_p[x]*cos(theta_pr[x]);
                     force_py[x]=force_p[x]*sin(theta_pr[x]);
                     force_a[x]=(force_py[x]*cos(theta_br[x])-force_px[x]*sin(theta_br[x]))/D[x];
                     force_b[x]=(force_px[x]*sin(theta_ar[x])-force_py[x]*cos(theta_ar[x]))/D[x];
                     
                     }
                     x=0;
                  
                  
                  cout<<" AXIAL LOADS IN A TWO BAR PINNED TRUSS\n\n\n"
                     <<"  TRUSS NO"<<setw(9)<<"TRUSS"<<setw(10)<<"LOAD"<<setw(10)<<"LOAD\n"
                     <<setw(18)<<"LOAD"<<setw(12)<<"BAR-A"<<setw(10)<<"BAR-B\n"
                     <<setw(19)<<"(LBS)"<<setw(11)<<"(LBS)"<<setw(10)<<"(LBS)\n";
                     row=1;
                 //COUTing
                 for (x;x<=2;x++){
                     cout<<"\n"<<setw(6)<<row<<setw(14)<<force_p[x]<<setw(11)<<force_a[x]<<setw(10)<<force_b[x]<<"\n";
                     row++;
                     }
                     x=0;
                     row=0;
                     cout<<"\n\n\nagain? 1 or 0\n";
                     cin>>run;
                     }
                     return 0;
                     }
kfmfe04 (788)
Suggestions:

1. fix your formatting - I can't tell where your blocks start and end
2. learn to use a debugger
Last edited on
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