Translation of Fortran 77 to C++ -How it works? - c++

Question

I am trying to replicate the following fortran 77 subroutine into c++.
subroutine calcul(nb, m, sd, x_min, n, y_w)
common / speed_1 / v_0
common / dat1 / x_m
common / dat2 / x_l0, x_r0, x_lq, e_l, e_r, a1, a2, b1
common / sor_arr / x(6500), y(6500), z(6500)
common / ef_mat / x_f(35000), y_f(35000)
y_m = y_w - rl_h
y_ma = rl_h
y_mi = -rl_h
x_ma = rb_h
x_mi = -rb_h
do 10 i = m, 1, -1
y_y = z(i) - y_m
if (y_y.gt.y_ma) goto 10
if (y_y.le.y_mi) goto 10
c1_s = y(i) / v_0
x_l = x_l0 + e_l*c1_s**a1
x_r = x_r0 + e_r*c1_s**a2
cl_r = x_r - x_l
c2_s = x(i) + x_min
i1 = 1
i2 = nb
i3 = 1
if (mod(i, 2).eq. 0) goto 20
i1 = nb
i2 = 1
i3 = -1
20 do 30 i = i1, i2, i3
r_m1 = float(i - 1)
x_q = c2_s + r_m1*sd - x_l
x_q = x_q * b1 / c1_r + xl_q
x_x = x_q - x_m
if (x_x.gt.x_ma) goto 30
if (x_x.le.x_mi) goto 30
n = n + 1
y_f(n) = y_y
x_f(n) = x_x
30 continue
10 continue
return
end
here is my translation
#include "stdafx.h"
#include <iostream>
using namespace std;
void calcul(int& nb, int& m, double& sd, double& x_min, int& n, double& y_w);
struct speed
{
double v_0;
};
struct dat1
{
double x_m;
};
struct dat2
{
double x_l0, x_r0, x_lq, e_l, e_r, rl_h, rb_h, a1, a2, b1;
};
struct sor_arr
{
double x[6500], y[6500], z[6500];
};
struct ef_mat
{
double x_f[35000], y_f[35000];
};
int main()
{
int nb1 = 10;
int m1 = 250;
double sd1 = 16;
double x1nmin = 1.e38;
int n1 = 0;
double yw1 = 0;
calcul(nb1, m1, sd1, x1nmin, n1, yw1);
system("PAUSE");
return 0;
}
void calcul(int& nb, int& m, double& sd, double& x_min, int& n, double& y_w)
{
struct speed sp;
struct dat1 d1;
struct dat2 d2;
struct sor_arr s;
struct ef_mat ef;
int i1;
int i2;
int i3;
double y_m;
double y_ma;
double y_mi;
double x_ma;
double x_mi;
double y_y;
double x_x;
double c1_s;
double x_l;
double x_r;
double cl_r;
double c2_s;
double r_m1;
double x_q;
y_m = y_w - d2.rl_h;
y_ma = d2.rl_h;
y_mi = -d2.rl_h;
x_ma = d2.rb_h;
x_mi = -d2.rb_h;
for (int i = m; i > 1; i--)
{
y_y = s.z[i] - y_m;
if (y_y > y_ma)
{
continue;
}
if (y_y <= y_ma)
{
continue;
}
c1_s = s.y[i] / sp.v_0;
x_l = d2.x_l0 + d2.e_l * pow(c1_s, d2.a1);
x_r = d2.x_r0 + d2.e_r * pow(c1_s, d2.a2);
cl_r = x_r - x_l;
c2_s = s.x[i] + x_min;
i1 = 1;
i2 = nb;
i3 = 1;
if (fmod(i,2)== 0)
{
for (int i = i1; i < i2; i+= i3)
{
r_m1 = float(i - 1);
x_q = c2_s + r_m1 * sd - x_l;
x_q = x_q * d2.b1 / cl_r + d2.x_lq;
x_x = x_q - d1.x_m;
if (x_x >= x_ma)
{
continue;
}
if (x_x < x_ma)
{
continue;
}
n = n + 1;
ef.y_f[n] = y_y;
ef.x_f[n] = x_x;
}
i1 = nb;
i2 = 1;
i3 = -1;
}
}
}
The errors are below. Can someone help me and tell me how to fix?
error C4700: uninitialized local variable 'sp' used
error C4700: uninitialized local variable 'd2' used
error C4700: uninitialized local variable 'd1' used

Answer 1

This is somewhat crazy and bold, but what you could try is to initialize your local variables.
For instance:
struct speed sp = {0};
struct dat1 d1 = {0};
struct dat2 d2 = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
If you go really crazy, you could even consider using other values than 0 - something that actually makes sense in this algorithm would be awesome!!!
Note: I have not the slightest clue about Fortran, nor did I look into further problems of your code.