Where did I go wrong in the for loop?

Question

C++ / C#

#include <stdio.h>
#include <cstdio>
#include <iostream>
#include <math.h>
#include<stdlib.h>
# define M_PI		3.14159265358979323846	/* pi */
using namespace std;
int main()
{
    float   x1,
            a,
            b,
            x,
            x2,
            k,
            z;

    system("cls");

    cout<< "Введите значение параметра а: " <<endl;
    cin >> a;
    cout<<"Введите значение параметра b: "<<endl;
    cin >> b;
    cout<<"Введите значение Хнач: "<<endl;
    cin>>x1;
    cout<<"Введите значение Хкон: "<<endl;
    cin>>x2;
    cout<<"Введите шаг k: "<<endl;
    cin>>k;
    cout<<"Таблица значений  z"<<endl;
    cout<<" ┌───────────┬────────────┐"<<endl;
    cout<<" │     x     │  z = f(x)  │"<<endl;
    cout<<" ├───────────┼────────────┤"<<endl;
    x=x1;
    for (;x <= x1;)
    {
        cout<<" │   "<<x<<"     │"<<endl;
        if (x <= a)
        {z= (4.1 + (7.0 * pow (x , 2)) + sin(8.2 * x + M_PI / 6));
            cout<<"  "<<z<<"  │"<<endl;}
            if (a < x && x < b)
            {z=sqrt((pow(cos(x),2) * pow(atan(x),2) * pow(x,2) + exp(3.0 * x + 10)));
                cout<<"  "<<z<<"  │"<<endl;}
                if (x >= b)
                {z=log10(asin(x)+acos(x)+pow(x,3.2));
                    cout<<"  "<<z<<"  │"<<endl;}
        x=x+k;
                }
    cout<<" └───────────┴────────────┘"<<endl;
    return 0;
}

All variables are real.

Answer 1

x=x1;
for (;x <= x1;)

I suspect it should be

x=x1;
for (;x <= x2;)