opengl is a graphics library while glut is not. You use glut with opengl to handle graphics. glut handles with mostly the input. It could create the graphics window, handle key input and some other fancy stuff. You use opengl to draw primitives onto the window that glut creates.
Iwhen to use a void function verses a bool or int or other type of function.
Whenever you create a function, you need to know what it does first. Does it sort an array, does it return the square of a number, does it print a triangle? Whatever, it does, you need to know its objective. After knowing its objective, you can easily figure out what type function you need. If it calculate the square of a number then make it return int, since it make sense to return the square of number. If it sorts an array, then it should be void function because array are pointers. If it just prints stuff then make it void because there is no need to return anything. So analyze what a function does and then look at the different possibilities, and pick one that fits the situation.
Also how to know what to call into the Function?
Again this is when you know what you want case. When you know what a function does and you know what you need it to do, then passing the required parameters isn't hard. Also you should have functions that you don't use. The reason you should create functions is for clarity, mostly. So if you decide to create a function make sure you use it, its not too big, and you know what its supposed to do. After …
Here is your program written better. You could have used switch statements, but I wasn't sure if you knew them.
Use code-tags.
/*
Pick a problem and solve
*/
#include <iostream>
using namespace std;
int main()
{
int x;
float a,b;
cout << "Hello, please pick a type of problem from the list. Please use the number of each: \n\n";
cout << "1. perimiter\n";
cout <<"2. area\n";
cout <<"3. addition\n";
cout <<"4. multiplication\n";
cout <<"5. subtraction\n";
cout <<"6. division\n";
cout <<"7. Quit program. \n";
cin >> x ;
//if x is less tha 1 or greater than 7 then throw error
while(x<1 || x >7)
{
cout << "Hello, please pick a type of problem from the list. Please use the number of each: \n\n";
cout << "1. perimiter\n";
cout <<"2. area\n";
cout <<"3. addition\n";
cout <<"4. multiplication\n";
cout <<"5. subtraction\n";
cout <<"6. division\n";
cout <<"7. Quit program. \n";
cin >> x ;
}
if(x == 1)
{
cout << "Enter the length: ";
cin >> a;
cout<<"\n\n";
cout << "enter the width: ";
cin >> b;
cout<<"\n\n";
cout << "The perimiter is: ";
cout << 2*(a+b);
}
else if( x == 2)
{
cout << "enter the length: ";
cin >> a;
cout<<"\n\n";
cout << "Enter the width: ";
cin >> b;
cout<<"\n\n";
cout << "The area is: ";
cout << a*b;
}
else if(x == 3)
{
cout << "Enter the first number: ";
cin >> a;
cout<<"\n\n";
cout << "Enter the second number: ";
cin >> …
also in the first program there is no memory leak.
Are you sure. His program is tricky in a sense that there is a memory leak. His function is definitely not doing what he thinks its doing.
One way to tell if you have memory leak is to see if every new is matched with delete. In your function, you allocate new memory for the array that is passed, which already has been allocated memory. So when inside the function, the arrays thats passed is located in whatever memory address that was reserved inside the function. When he exits out that functions, that memory is no longer in play. Inside main he has already the array pointing at a specific address.
So the memory inside the function has a leak. Also you use 2 instances of new but only 1 delete. Does that give you a hint?
forgot the int in int main(), or does your compiler support default int. And system command, argghhh. Throw them away. cin.get() would be a better choice to "pause" the screen.
1)i want to set the lines at run time.( w.r.t. x-axis,y-axis,clockwise and anti-clockwise)
Ok whats the problem. In your drawFunc have the (X_i,Y_i,Z_i) and the (X_f, Y_f, Z_f) as variables and change it accordingly. Maybe if '+' is pressed, increase the length of each X coord by 1 unit...
2)i want to detect collision of a circle with the lines(which may be in slope), and after collision the circle should bounce in a paricular direction.....
Option # 1) Check if the lines is within the circle's position. The circle position has an X,Y,Z coordinate. If the line is within the area of the circle then there is a collision. And move the circle -x.
Option # 2) Check if the circle + radius is within the Top height and the low height of the line. If so then check if its X position + radius is within the lines X coordinate of the line. If so then there is a collision and move circle to -x, maybe by making its x velocity = -x velocity.
@VernonDozier : wow. When someone writes that long of a paragraphs you know he means it
@xfreebornx take a look :
int option = 0;
int quit = -1;
do
{
cout <<"Welcome to student recording system"<<endl;
cout <<"Please choose one of the following option"<<endl;
cout <<"1. Insert new record"<<endl;
cout <<"2. Sort record"<<endl;
cin >> option;
switch(option)
{
case 1: insert(array); break;
case 2: cout<<"you picked sorting\n".
cout<<"Now sorting\n";
mySort(array, numberOfElements); //see way below
cout<<"Sorting done\n";
break;
}
}while(option != quit)
//after end of main
bool mySort(int array[], int numberOfElements)
{
if(numberOfElements == 0) return false;
//Either create your own myCompareFunction, or use the ones that I provided in the previous post.
std::sort(array,array+ numberOfElements, myCompareFunction);
return true;
}
To use the keyword delete, for your array, you have to dynamically allocate memory. Since you are not doing that you can do some other things. One that comes to mind is delete all data by assigning them 0 and/or "".
To sort the members you can use std::sort, with your own compare function.
int numX;
int numY;
int numZ;
int sum1 = numX - numZ;
int sum2 = numX - numY + numZ;
int sum3 = numX + numY;
int sum4 = numX + numY + numZ;
int sum5 = numX;
int sum6 = numX - numY - numZ;
int sum7 = numX - numY;
int sum8 = numX + numY - numZ;
int sum9 = numX + numZ;
int totalA = sum1 + sum2 + sum3;
int totalB = sum4 + sum5 + sum6;
int totalC = sum7 + sum8 + sum9;
int totalD = sum1 + sum4 + sum7;
int totalE = sum2 + sum5 + sum8;
int totalF = sum3 + sum6 + sum9;
Is useless because numX,numY,numZ is not initialized. You need to first get num* then calculate it. What you are doing is calculating junk, then getting num* then showing the junk you calculated.
Again get user input first into numX,numY,numZ, then calculated whatever you need to calculate.
No, not finding parts of the file but read the whole file, while analyzing it in the process.
Assuming the file is the something like this :
Info.txt --------------------------------------------- Password = hello_world Active t = false --------------------------------------------- 1) open up a file with fstream 2) read first line into string 3) increment the string until it reaches the equal sign, then the password something like this :
while( *stringVariable++ != '=' ) ; //increment until the = sign
while( ! (isalpha (*stringVariable++) ) ); //increment untill you reached the first letter in the password.
4) Now you have got the password. save it. 5) read the next line. do the same process like in # 3 6) compare stringVariable to flase or true. Set bool variable accordingly.
Nested class means that a class is "nested" i.e, in scope of the outer class. Thus the code :
class Outer
{
public:
class Inner{ ... };
}
has a nested class called Inner because its inside the scope of the outer class. And if public, it could be used with the scope resolution operator ::, like so Outer::Inner::someFunc
For your question # 2, you can use the public interface of the elevator, but it should be only allowed to be used by passenger, and not the building class.
And I am not sure what question # 1 is asking. Care to elaborate.
