如何从这个 function 取回我的主要 function 的迭代值？

Question

I'm trying to return the iterations back to main from JacobiMethod , but it still shows 0 even when I write return iterations;

int JacobiMethod(double T[N][N], double c[N], double x[N], int iterations)
{
    double x_new[N];
    double x_prev[N];
    double tmp=0;
    while(magnitudeVectorDiff(x_new, x_prev) != 1)
    {   
        for(int i=0; i<N; i++)
        {
            for(int j=0; j<N; j++)
            {
                tmp=tmp+T[i][j]*x[j];
            }
            x_new[i]=tmp+c[i];
            tmp=0;
        }
        for(int i=0; i<N; i++)
        {
            x_prev[i]=x[i];
            x[i]=x_new[i];
        }
        iterations++;
    }
    return iterations;
}

int main()
{
    double A[N][N];
    double v[N];
    double x[N] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
    double LU[N][N];
    double Dinv[N][N];
    double T[N][N];
    double c[N];
    double x_new[N];
    double x_prev[N];
    int iterations=0;
    read_data_from_file(A, v);
    splitting_array(A, LU, Dinv);
    T_and_c(LU, Dinv, v, T, c);
    JacobiMethod(T, c, x, iterations);
    iterations=JacobiMethod(T, c, x, iterations);
    printArray(A);
    printVectorV(v);
    printf("Completed %d iterations (for tolerance = %lf).\n", iterations, TOL);
    printf("%d\n", iterations);
    printVector(x);
    return 0;
}

Edit: I've added the main function above but I didn't include all the other functions of the program, as they are not that important for this question.

Answer 1

You need to store the return of your function in your variable for it to change:

iterations = JacobiMethod(T, c, x, iterations);

And in your function, as explined in the comment, you can return iterations and the return type of your function should be int .

Note that the iterations variables in the main and in your function JacobiMethod are 2 different variables. They are both local variables available only in their respective functions. They just have the same name, but they are not the same variable.

When the variable iterations changes in JacobiMethod , the variable in the main doesn't change.

That's why you need to return the value from your function and assign the return of your function in the main.