# include <iostream>
#include <string> 
#include <cmath>
#include <cstdlib>
#include <iomanip>
using namespace std;
#define PI 3.1416
//double log5(double );
// lets define log base 5
double log5(double x){
	double y = log2(x)/log2(5);
	return y;
}

int solve_a_problem(void);
int main(){

// arithmetics
	int a=3, b=7,c=10+3;
	c=17+5; a=23-c; 
	int d=c*2;
	cout <<"\n\n ARITHMETIC OPERATORS\n";
	cout<<"first orund a="<<a<<"   b="<<b<<"   c="<<c<<"   d="<<d<<"\n";
	b=a%2;
	a = 5/2; 
	cout<<"second orund a="<<a<<"   b="<<b<<"   c="<<c<<"   d="<<d<<"\n";
	a=b=c=d=10;
	cout<<"third orund a="<<a<<"   b="<<b<<"   c="<<c<<"   d="<<d<<"\n";
	
//	return 0;	
	
//integer division	
	int a1 = 5/2;
	double a2=5/2;
	double a3= 5.0/2;
	double a4 = (double)5/2;
	cout<<"\n\nINEGER DIVISION\n a1="<<a1<<"   a2="<<a2<<"   a3="<<a3<<"   a4="<<a4<<"\n";
	
//	return 0;
	
//math expressions and precedence 	
	int n0 = 12 - 6 + 3, n1,n2,n3,n4;
	n1 = 12 - 6/3;
	n2 = 3+5+8;
	n3 = 3+5+8/3;
	n4 = (3+5+8)/3;
	double n5 = (double)(3+5+8)/3;
	cout<<"\n\nMATH, PRECEDENCE\n n0="<<n0<<"   n1="<<n1<<"   n2="<<n2;
	cout <<"   n3="<<n3<<"   n4="<<n4<<"   n5="<<n5<<"\n";
	
	int n6,n7,n8; 
	n6= 6-3*2+7-1;
	n7 = (6-3)*2+7-1;
	n8 = (6-3)*(2+7)-1;
	int n9 = 6-3<<2*2+1;
	cout <<"n6="<<n6<<"   n7="<<n7<<"   n8="<<n8<<"   n9="<<n9<<"\n";
	int n10 = 6+15%10 +2;
	int n11 = (6+15)%10 +2;
	cout <<"n10="<<n10<<"   n11="<<n11<<endl;
//	return 0;

//logarithm, exponential **** note the header cmath library
	double y0 = pow(5.0,3);//results in x=125
	double y1 = log(100);//returns y=4.605..., natural log
	double y2=log10(100); //returns y=2, log base 10
	double y3=log2(100); //returns y=6.64..., log base 2
	double y4=log10(pow(100.0,4)); //returns what?
	cout<<"\n\nEXP and LOG\n y0="<<y0<<" y1="<<y1<<"   y2="<<y2<<"   y3="<<y3<<"   y4="<<y4<<"\n";
	// write a function for log base 5
	double y5=log5(28);
	cout <<"   y5="<<y5<<"\n";

//	return 0;
	
//sqrt, more math
	double z0=sqrt(81);
	double z1=abs(-23.65);
	double z2,z3,z4;
	z2=cos(PI/2);
	z3= exp(2);
	z4=fmod(12.5,3.8);
	cout<<"\n\nMORE MATH\n z0="<<z0<<"  z1="<<z1<<"   z2=cos(PI/2)="<<z2<<"   \nz3="<<z3<<"   z4="<<z4<<"\n";
//	cout<<"sizeof long is "<<sizeof(long)<<"\n";

//	return 0;	
	
	
//overflow
	int t1=150000,t2=150000;
	int t3= t1*t2;
	long t4= (long)t1*(long)t2;
	cout <<"\n\n OVERFLOW\n 150000x150000 should be 22500000000 \n but as type int is t3="<<t3;
	cout<<"\nas type long we get t4="<<t4<<"\n";

//	return 0;
//compound operators
	a1=5; a1+=4; 
	a2=5; a2-=4; 
	int b1=7; b1*=a1; 
	int b2 =10; b2/=5; 
	cout<<"\n\nCOMPOUND OPERATORS \na1="<<a1<<" a2="<<a2<<" b1="<<b1<<" b2="<<b2<<"\n";

//	return 0;
//random numbers *** note the header cstdlib
	int r1,r2=rand(),r3; 
	r1= rand(); r3=rand();
	cout <<"\n\nRANDOM NUMBERS\n "<<r1<<"  "<<r2<<"  "<<r3<<"\n";	
	unsigned seed=time(0);
	srand(seed);
	r1= rand(); r2=rand(); r3=rand();
	cout <<r1<<"  "<<r2<<"  "<<r3<<"\n";

//	return 0;

		
//format the output *** header iomanip required for setw() 
	z0=12345.6789;
	cout<<"\n\n FORMATTED OUTPUT\n z0="<<z0;
	cout<<"\n "<<setw(15)<<z0;
	cout<<"\n"<< setprecision(9)<<z0;
	cout<<"\n"<<setprecision(3)<< z0;
	cout<<"\n"<<setprecision(2)<<fixed<< z0;
	cout<<"\n"<<setprecision(3)<<fixed<<right<<"|"<<setw(15)<< z0;
	cout<<"\n"<<setprecision(3)<<fixed<<left<<"|"<<setw(15)<< z0<<"|\n";
//	return 0;	
	
//input a string with spaces
	// string sz; 
	// cout<<"\n\n GETLINE, CIN.GET\n First round input name:";
	// cin>>sz;
	// // cout<<" first round name sz="<<sz<<endl;
	// // cin.ignore(20,'\n');
	// string sz2; cin >>sz2;
	//   	cout<<" first round sz="<<sz<<" sz2="<<sz2;
	//  	
	// cout<<"\n\n Second round input name:";
	// cin.ignore(20,'\n');
	// getline (cin, sz);
	// cout<<"second round sz="<<sz;
	// cout <<"\n";	
	

//	return 0;

//relational operators
	bool v1 = 2>3;
	bool v2 = (5>=5);
	bool v3 = !23;
	cout<<"\n\nRELATIONAL OPERATORS\n v1="<<v1<< " v2="<<v2<< " v3="<<v3;
	cout<<"\n sizeof(bool)="<<sizeof(bool)<<endl;

	
//	return 0;	
//if statement
	a=9; b=18; cout<<"\n\nIF STATEMENT\n a="<<a<<" b=" <<b<<"\n";
	if (a>b) {
		cout <<"a>b";
		cout <<" branch 1 executed\n";
	}
	if(b>a) {
		cout <<"b>a"; cout <<" branch 2 executed\n";
	}
	if(b==a) {
		cout <<"b==a"; cout <<" branch 3 executed\n";
	}

	if(10+5-2*7.5){ cout<<" \ngot true 1";}
	else cout<<"\n got false 1";

	if("virgil"){ cout<<" \ngot true 2";}
	else cout<<"\n got false 2";

	if(""){ cout<<" \ngot true 3";}
	else cout<<"\n got false 3";
	
	int x=0;
	if(x==1){ cout<<" \ngot true 4";}
	else cout<<"\n got false 4";
	cout<<endl;	

//	return 0;
//nested if
	a=0; b=0;
	// cout<<"\n\n input two numbers:";
	// cin>>a;
	// cin>>b;
	cout << "\n\n NESTED IF\n a="<<a<<"  b="<<b<<endl;

	if (a>0){
		if(b>0){cout << "a>0 and b>0";}
		else if (b<0){cout << "a>0 and b<0";}
			else {cout << "a>0 and b=0";}
	}
	else if (a<0){
		if(b>0){cout << "a<0 and b>0";}
		else if (b<0){cout << "a<0 and b<0";}
			else {cout << "a<0 and b=0";}
	}
	else {
		if(b>0){cout << "a=0 and b>0";}
		else {
			if (b<0){cout << "a=0 and b<0";}
			else {cout << "a=0 and b=0";}
		}
	}
	
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
//	return 0;

//compare floats VS compare doubles
	
	double f1=10.01, f2=10.010000000000001; cout<<"\n\nROUNDING ERROR?\n" <<f1<<" "<<f2<<endl;
	if (f1==f2) {cout <<"f1 same as f2";}
	else cout << "f1 different than f2";
	cout << endl;

//	return 0;
	
//logical operators	
	a=1; b=5;
	v1= !a||b && !b||7>a && !7 >= -1&& !2*5;
	v2= (!a||b) && (!b||7>a) && (!7 >= (-1&& !2*5));
	cout<<"\n\nLOGICAL OPERATORS, PRECEDENCE, SHORT CIRCUIT \n v1="<<v1<<" v2="<<v2;
	n1=0; v1 = (5>2)||(n1=1);
	cout << "\n v1="<<v1<<" n1="<<n1;
	n2=1; v2 = (n2=0)&&(n1=1);
	cout << "\n v2="<<v2<<" n1="<<n1<<" n2="<<n2;
	cout<<endl;

//	 return 0;


// compare strigs, chars
	char cx= 'A';
	char dx='B';
	
	cout <<"\n\n COMAPRE STRINGS, CHARS\n c="<<cx<<" d="<<dx<<"\n";
	if (cx==65) { cout << "true, cx='A'";} 
	else {cout<< " false cx is not 'A'";}
	
	if (cx>dx) { cout <<  "\n cx bigger than dx";} 
	else {cout<<"\n cx smaller than dx";}

	if ((cx>=65) && (cx<=90)) { cout << "\n c is a capital letter";}		
//	return 0; 
	
	string sx = "1234";
	string sy = "1234"; 
	cout << "\n\nsx="<<sx<<" sy="<<sy<<endl; 
	if(sx<sy){ cout << "sx<sy";}
	if(sx>sy){ cout << "sx>sy";}
	if(sx==sy){ cout << "sx==sy";}
//	t1 = strcmp(sx,sy);
	t1 = strcmp(sx.c_str(),sy.c_str());
	cout << "\nstrcmp gives t1="<<t1;

	cout <<endl;
//	return 0;
	
//conditional operator	
	int score = 10;
	sx= score<75 ? "bad" : "good";
	cout <<"\n\n CONDITIONAL OPERATOR\n sx="<<sx;
	
	score>20 ? a = 10 : a=20;
	cout << "\na="<<a;
	
	cout<<"\n";
		
//	return 0;	
	
	
//switch
//*
	int selection;

	cout<< "\n\n TESTING SWITCH STATEMENT\n1.Movies  2.Music  3.Pictures\n";
	cout<< "Please make a selection (1-3):"; cin>>selection; 
	switch(selection) {
		case 1: //do some things with Movies; 
		cout<<"You selected Movies... ";
		cout<<"Favoite actor: Robert De Niro\n";
		break;
		case 2: //do some things with Music; 
			cout<<"You selected Music.";
			cout<<" Favorite song: Chan Chan by Compay Segundo\n";
	//	break;
		case 3: //do some things with Pictures
			cout<<"You selected Pictures. ";
			cout<<"Fovorite: Einstein portrait\n";
	//	break;
		default: cout<< "Your selection is not valid\n"; //repeat=0;
	}	
	
//*/	
	
	return 0;	


// solve the train intersection problem	
	solve_a_problem();
	return 0;	


}

int solve_a_problem(){
	//input, validate
	double d,t1,s1,t2,s2;
	cout<<"\n\n SOLVING THE TRAINS INTERSECTION\n";
	cout<<"distance in ft between A and B="; cin>>d; 
	if (d<=0) {cout<<"Invalid distance. EXIT"; return 0;}
	cout <<"time in seconds departure for train ab (A to B)="; cin>>t1;
	if (t1<=0) {cout<<"Invalid time. EXIT"; return 0;}
	cout <<"speed in ft/s for train ab (A to B)="; cin>>s1;
	if (s1<=0) {cout<<"Invalid speed. EXIT"; return 0;}
	cout <<"time in seconds departure for train ba (B to A)="; cin>>t2;	
	if (t2<=0) {cout<<"Invalid time. EXIT"; return 0;}
	cout <<"speed in ft/s for train ba (B to A)="; cin>>s2;
	if (s2<=0) {cout<<"Invalid speed. EXIT"; return 0;}

	//compute
	double t = (d+t1*s1 +t2*s2) / (s1+s2);
	double d1=(t-t1)*s1; 
	double d2=(t-t2)*s2; 

	//verify, output
	if (d1<0 || d1>d) {cout <<"\ndo not intersect"; return 0;}
	if (d2<0 || d2>d) {cout <<"\ndo not intersect"; return 0;}
	cout <<"\n trains intersect at time="<<t<<", dist form A="<<d1;
	cout <<", dist from B="<<d2<<endl;
	return 0;
}