что не правильно ?

#define _USE_MATH_DEFINES
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
double x;
double y;
double x1,x2,h;
cin >> x1;
cin >> x2;
cin >> h;
for(x = x1; x < x2; x += h)
y=pow(M_E,x)*cos(M_PI/180/4)*cos(x*sin(x));
cout << y;
system("pause");
return 0;
}

y=pow(M_E,(x*cos(M_PI_4)))*cos(x*sin(x));

#include<cstring>
#include<iostream>
using namespace std;
int main()
{
char str1[] = "The laboratory ";
char str2[] = "work ";
char str3[] = "number 6.";
char str4[100] = {0};
for(int i = 0;i < strlen(str1);i++)
str4[i] = str1[i];
int j;
for(int i = strlen(str1), j = 0; j < strlen(str2);i++, j++)
str4[i] = str2[j];
for(int i = strlen(str1) + strlen(str2), j = 0; j < strlen(str3); i++,j++)
str4[i] = str3[j];
cout << str4;
return 0;
}

#include<cstring>
#include<iostream>
using namespace std;
int main()
{
char str1[] = "The laboratory ";
char str2[] = "work ";
char str3[] = "number 6.";
char*str4;
int l1=strlen(str1);
int l2=strlen(str2);
int l3=strlen(str3);
str4=new char[l1+l2+l3+1];
for(int i = 0;i < l1;i++)
str4[i] = str1[i];
for(int i =l1, j = 0; j <l2;i++, j++)
str4[i] = str2[j];
for(int i = l1+ l2, j = 0; j <l3; i++,j++)
str4[i] = str3[j];
cout << str4;
delete [] str4;
return 0;
}