我对 C++ 有疑问，因为它拒绝显示答案而且我不知道问题出在代码中

Question

 #include <iostream>
#include <math.h>
#include <iomanip>
#include <tchar.h> using namespace std;

int _tmain(int argc, _TCHAR* argv[]) {
    setlocale(LC_CTYPE, "Russian");
    double x;
    for (x = 2; x < 6.3; x + 0.4);
    {
        double Rez, Rez1;
        Rez = pow(x, 4) + 2 * pow(x, 2) + 3;
        Rez1 = cos(3 * x) + exp(-2 * x);
        cout << Rez << Rez1;
    }
    system("Pause");
    return 0;

it supposed to count equations with each value of X in the range from 2 to 6.3, with a step of 0.4 aka 2, 2.4, 2.8, etc.

Answer 1

The problem was with the final semicolon as someone in the comments suggested. Just due to that semicolon, x's value was incremented above 6.4 in the 1st iteration and only 1 iteration was taking place. Also the variable x needs to be incremented in an appropriate way: Here is the working code:

#include <iostream>
#include <math.h>
#include <iomanip>
#include <tchar.h> 
using namespace std;

int _tmain(int argc, _TCHAR* argv[]) 
{
    setlocale(LC_CTYPE, "Russian");
     double x=2;
    for ( x = 2 ; x < 6.3;  x = x + 0.4 )
    {
        double Rez, Rez1;
        Rez = pow( x, 4) + 2 * pow( x, 2) + 3;
        Rez1 = cos(3 * x) + exp(-2 * x);
        cout <<"Result 1:" <<Rez <<"  Result 2:"<< Rez1<< endl;
    }

    system("Pause");
    return 0;
}