C++ project help Generating variables.

Discussion in 'C++' started by Nutkin, Nov 27, 2006.

  1. Nutkin

    Nutkin Guest

    Basicly i have to make a program that calculates the distance between x
    and y points in 2d space.
    the code basicly goes like this


    1. User says how many points they have (max of 10)

    2. User enters points

    3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    between 2 points

    4. It displays the length between the first and last point.


    My problem is how do i accept the data. im not sure how to vary the
    number of inputs or how to declare the variables. like say the user
    wants 6 points how do i let the program know only to ask the user for 6
    points. and then how do i do the same calculation for each of those
    points.


    i tried using a while loop and heres my code so far.

    #include <iostream>;
    #include <cmath.h>

    using namespace std;

    double length(double xa,double xb,double ya,double yb)
    {
    double length=0;

    length=sqrt(((xb-xa)*(xb-xa))+((yb-ya)*(yb-ya)));

    return (length);

    }

    int main()

    int points=0;
    int ans=0;
    double length(double,double,double,double)
    double xa=0;
    double xb=0;
    double ya=0;
    double yb=0;



    cout <<"How many points would you like to input (Max 10)?\n\n";
    cin >>points;


    while (points > 1)
    {
    cout <<"Please enter an x value\n";
    cin >>xa;
    cout <<"Please enter a y value\n";
    cin >>ya;
    cout <<"Please enter an x value\n";
    cin >>xb;
    cout <<"Please enter a y value\n";
    cin >>yb;

    ans=ans+length(xa,xb,ya,yb)

    points=points-1;
    }

    return (0);



    Im using VC++


    i know the codes a little crappy but hey thats what help is for right
    :)

    Thanks in advance to any genius who can sort this mess out.
     
    Nutkin, Nov 27, 2006
    #1
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  2. Nutkin

    Guest

    On Nov 27, 8:07 am, "Nutkin" <> wrote:
    > Basicly i have to make a program that calculates the distance between x
    > and y points in 2d space.
    > the code basicly goes like this
    >
    > 1. User says how many points they have (max of 10)
    >
    > 2. User enters points
    >
    > 3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    > between 2 points
    >
    > 4. It displays the length between the first and last point.
    >
    > My problem is how do i accept the data. im not sure how to vary the
    > number of inputs or how to declare the variables. like say the user
    > wants 6 points how do i let the program know only to ask the user for 6
    > points. and then how do i do the same calculation for each of those
    > points.


    I thin you want to use a container-class to store the points in,
    something like this:

    #include <iostream>
    #include <vector>
    #include <map> // to get std::pair

    int main()
    {
    std::vector<std::pair<double, double> > points; // stores the points
    int nrPoints;

    std::cout << "Number of points: ";
    std::cin >> nrPoints;

    for (int i = 0; i < nrPoints; ++i) // For-loops are nice, but can use
    while too
    {
    double x, y;
    std::cout << "Enter x: ";
    std::cin >> x;
    std::cout << "Enter y: ";
    std::cin >> y;

    points.push_back(std::make_pair(x,y)); // add the point to the
    collection
    }

    // Calculate distance

    return 0;
    }

    Then you can access the points just like this:

    points[2].first // The x-value of the third point (starts from 0)
    points[2].second // The y-value of the second point

    To get the distance I'd do something like this:

    for (int i = 0; i < nrPoints - 1; ++i) // Notice nrPoints -1
    {
    ans += length(points.first, points[i+1].first, points.second,
    points[i+1].second)
    }

    You could also use two vectors, one for x- and one for y-values.

    --
    Erik Wikstöm
     
    , Nov 27, 2006
    #2
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  3. Nutkin

    Steve Pope Guest

    <> wrote:

    >I thin you want to use a container-class to store the points in,
    >something like this:
    >
    >#include <iostream>
    >#include <vector>
    >#include <map> // to get std::pair


    Another possibility is using std::complex<double> for the (x,y) pair.

    Steve
     
    Steve Pope, Nov 27, 2006
    #3
  4. Nutkin

    Nutkin Guest

    wrote:
    > On Nov 27, 8:07 am, "Nutkin" <> wrote:
    > > Basicly i have to make a program that calculates the distance between x
    > > and y points in 2d space.
    > > the code basicly goes like this
    > >
    > > 1. User says how many points they have (max of 10)
    > >
    > > 2. User enters points
    > >
    > > 3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    > > between 2 points
    > >
    > > 4. It displays the length between the first and last point.
    > >
    > > My problem is how do i accept the data. im not sure how to vary the
    > > number of inputs or how to declare the variables. like say the user
    > > wants 6 points how do i let the program know only to ask the user for 6
    > > points. and then how do i do the same calculation for each of those
    > > points.

    >
    > I thin you want to use a container-class to store the points in,
    > something like this:
    >
    > #include <iostream>
    > #include <vector>
    > #include <map> // to get std::pair
    >
    > int main()
    > {
    > std::vector<std::pair<double, double> > points; // stores the points
    > int nrPoints;
    >
    > std::cout << "Number of points: ";
    > std::cin >> nrPoints;
    >
    > for (int i = 0; i < nrPoints; ++i) // For-loops are nice, but can use
    > while too
    > {
    > double x, y;
    > std::cout << "Enter x: ";
    > std::cin >> x;
    > std::cout << "Enter y: ";
    > std::cin >> y;
    >
    > points.push_back(std::make_pair(x,y)); // add the point to the
    > collection
    > }
    >
    > // Calculate distance
    >
    > return 0;
    > }
    >
    > Then you can access the points just like this:
    >
    > points[2].first // The x-value of the third point (starts from 0)
    > points[2].second // The y-value of the second point
    >
    > To get the distance I'd do something like this:
    >
    > for (int i = 0; i < nrPoints - 1; ++i) // Notice nrPoints -1
    > {
    > ans += length(points.first, points[i+1].first, points.second,
    > points[i+1].second)
    > }
    >
    > You could also use two vectors, one for x- and one for y-values.
    >
    > --
    > Erik Wikstöm




    I think thats a bit over my head but i can see where you are coming
    from. So i shall study it a bit more and see if i can get away with
    using it. But we havnt been taught vectors yet so im not sure if it
    will be valid. Thanks so much for giving me some options im gonna have
    a play about with ti now.



    If anyone has a more basic idea would be awesome..
     
    Nutkin, Nov 27, 2006
    #4
  5. Nutkin

    kwikius Guest

    Nutkin wrote:
    > Basicly i have to make a program that calculates the distance between x
    > and y points in 2d space.
    > the code basicly goes like this
    >
    >
    > 1. User says how many points they have (max of 10)
    >
    > 2. User enters points
    >
    > 3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    > between 2 points
    >
    > 4. It displays the length between the first and last point.
    >
    >
    > My problem is how do i accept the data. im not sure how to vary the
    > number of inputs or how to declare the variables. like say the user
    > wants 6 points how do i let the program know only to ask the user for 6
    > points. and then how do i do the same calculation for each of those
    > points.
    >
    >
    > i tried using a while loop and heres my code so far.


    Your code looks to be on the right track, but I would rethink using an
    int for the ans variable. Should it not be capable of holding values
    like 0.5 too?

    For checking the users input, you could use an infinite loop and break
    out of it when you have checked the input is valid:

    int points = 0;
    // for loop continues until number of points is valid
    for (;;){
    std::cout <<"How many points would you like to input (Max 10)? :
    ";
    std::cin >> points
    if ((points < 2) || (points > 10)){
    std::cout << "number of points has to be between 2 and 10\n";
    }
    else {
    break;
    }
    }

    you could also use a while loop or a do loop instead of course.

    regards
    Andy Little
     
    kwikius, Nov 27, 2006
    #5
  6. Nutkin

    Nutkin Guest

    kwikius wrote:
    > Nutkin wrote:
    > > Basicly i have to make a program that calculates the distance between x
    > > and y points in 2d space.
    > > the code basicly goes like this
    > >
    > >
    > > 1. User says how many points they have (max of 10)
    > >
    > > 2. User enters points
    > >
    > > 3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    > > between 2 points
    > >
    > > 4. It displays the length between the first and last point.
    > >
    > >
    > > My problem is how do i accept the data. im not sure how to vary the
    > > number of inputs or how to declare the variables. like say the user
    > > wants 6 points how do i let the program know only to ask the user for 6
    > > points. and then how do i do the same calculation for each of those
    > > points.
    > >
    > >
    > > i tried using a while loop and heres my code so far.

    >
    > Your code looks to be on the right track, but I would rethink using an
    > int for the ans variable. Should it not be capable of holding values
    > like 0.5 too?
    >
    > For checking the users input, you could use an infinite loop and break
    > out of it when you have checked the input is valid:
    >
    > int points = 0;
    > // for loop continues until number of points is valid
    > for (;;){
    > std::cout <<"How many points would you like to input (Max 10)? :
    > ";
    > std::cin >> points
    > if ((points < 2) || (points > 10)){
    > std::cout << "number of points has to be between 2 and 10\n";
    > }
    > else {
    > break;
    > }
    > }
    >
    > you could also use a while loop or a do loop instead of course.
    >
    > regards
    > Andy Little



    Ive now been told i must use arrays ahhh i hate my uni.
     
    Nutkin, Nov 27, 2006
    #6
  7. Nutkin

    Guest

    On Nov 27, 10:28 am, "Nutkin" <> wrote:
    > Ive now been told i must use arrays ahhh i hate my uni.


    Then first read in the number of points wanted then dynamically
    allocate the array using new, then the rest should be quite like what's
    already discussed. Don't forget to deallocate the array when you are
    done with it (using delete).

    --
    Erik Wikström
     
    , Nov 27, 2006
    #7
  8. Nutkin

    rossum Guest

    On 27 Nov 2006 02:52:59 -0800, ""
    <> wrote:

    >On Nov 27, 10:28 am, "Nutkin" <> wrote:
    >> Ive now been told i must use arrays ahhh i hate my uni.

    >
    >Then first read in the number of points wanted then dynamically
    >allocate the array using new, then the rest should be quite like what's
    >already discussed. Don't forget to deallocate the array when you are
    >done with it (using delete).


    No need to bo so complex. We know that there will be a maximum of 10
    points so allocate a fixed size array big enough to hold 10 points.
    With small amounts of data there is no need to get into the
    complexities of dynamic arrays. The OP may not have studied new and
    delete yet, this assignment seems to be quite simple and likely to be
    early in the course.

    rossum
     
    rossum, Nov 27, 2006
    #8
  9. Nutkin

    Guest

    On Nov 27, 3:10 pm, rossum <> wrote:
    > On 27 Nov 2006 02:52:59 -0800, ""
    >
    > <> wrote:
    > >On Nov 27, 10:28 am, "Nutkin" <> wrote:
    > >> Ive now been told i must use arrays ahhh i hate my uni.

    >
    > >Then first read in the number of points wanted then dynamically
    > >allocate the array using new, then the rest should be quite like what's
    > >already discussed. Don't forget to deallocate the array when you are
    > >done with it (using delete).No need to bo so complex. We know that there will be a maximum of 10

    > points so allocate a fixed size array big enough to hold 10 points.
    > With small amounts of data there is no need to get into the
    > complexities of dynamic arrays. The OP may not have studied new and
    > delete yet, this assignment seems to be quite simple and likely to be
    > early in the course.


    Right you are, I forgot about the max 10 part.

    --
    Erik Wikström
     
    , Nov 27, 2006
    #9
  10. Nutkin

    Kevin Handy Guest

    Nutkin wrote:
    > Basicly i have to make a program that calculates the distance between x
    > and y points in 2d space.
    > the code basicly goes like this
    >
    >
    > 1. User says how many points they have (max of 10)
    >
    > 2. User enters points
    >
    > 3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    > between 2 points
    >
    > 4. It displays the length between the first and last point.


    Why bother entering all the data points, when you are
    only going to display the first and last points entered,
    ignoring the rest? If you made me enter 1000 points,
    then ignored all but the first and last entry, I'd
    probably get pissed off.

    > My problem is how do i accept the data. im not sure how to vary the
    > number of inputs or how to declare the variables. like say the user
    > wants 6 points how do i let the program know only to ask the user for 6
    > points. and then how do i do the same calculation for each of those
    > points.


    Assuming you want the difference between point 1 and
    last entered point, just enter/store point 1, then loop
    through additional points (input, calculate, display, repeat).
    Only need storage for two points at a time (point 1
    and current point)

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    Kevin Handy, Nov 27, 2006
    #10
  11. Nutkin

    BobR Guest

    wrote in message ...

    /* """

    I thin you want to use a container-class to store the points in,
    something like this:
    #include <iostream>
    #include <vector>
    #include <map> // to get std::pair
    int main(){
    // stores the points int nrPoints;
    std::vector<std::pair<double, double> > points;
    std::cout << "Number of points: ";
    std::cin >> nrPoints;
    for (int i = 0; i < nrPoints; ++i){
    // For-loops are nice, but can use while too
    double x, y;
    std::cout << "Enter x: ";
    std::cin >> x;
    std::cout << "Enter y: ";
    std::cin >> y;
    // add the point to the collection
    points.push_back(std::make_pair(x,y));
    }
    // Calculate distance
    return 0;
    }

    Then you can access the points just like this:
    points[2].first // The x-value of the third point (starts from 0)
    points[2].second // The y-value of the second point

    To get the distance I'd do something like this:
    for (int i = 0; i < nrPoints - 1; ++i){ // Notice nrPoints -1
    ans += length(points.first, points[i+1].first, points.second,
    points[i+1].second)
    }

    You could also use two vectors, one for x- and one for y-values.
    Erik Wikstöm

    """ */

    You guys (include Steve Pope) are involving way too much complexity (yes,
    Steve, a pun). You're not trying to hide simplicity from the boss, but, help
    a starting student.

    If the OP could use 'vector' (later states (s)he can't), a simple vector of
    struct would make life easier (in the OPs assignment).

    // class Point{ public: // same thing
    struct Point{
    double x;
    double y;
    Point() : x(0), y(0){}
    };


    { // main() or function

    std::vector<Point> Parray( 10 );

    Parray.at(0).x = 23.45;
    Parray.at(0).y = 67.89;

    std::cout<< "x=" << Parray.at(0).x
    << ", " << Parray.at(0).y <<std::endl;

    for(size_t i( 0 ); i < Parray.size(); ++i){ // Notice NO "nrPoints -1"
    std::cout<< "x=" << Parray.at( i ).x
    << ", " << Parray.at( i ).y <<std::endl;
    } // for(i)

    } // end

    That's my 0.002 pico-cents **opinion**.
    --
    Bob R
    POVrookie
     
    BobR, Nov 27, 2006
    #11
  12. Nutkin

    BobR Guest

    Nutkin wrote in message ...
    >
    >Ive now been told i must use arrays ahhh i hate my uni.


    It's just the ol' "pencil-n-paper before calculator" thing.

    Since you know the maximum number of elements, you could just set up the
    array to max, and put the limits in input/output.

    // #includes here
    int main(){
    std::size_t const sz( 10 );
    double X[ sz ] = {0};
    double Y[ sz ] = {0};
    // - get the max number from user and check for range. -
    for( std::size_t i( 0 ); i < NumFromUser; ++i ){
    cin >> X[ i ];
    cin >> Y[ i ];
    if( not cin ){
    std::cerr <<"ERROR!"<<std::endl;
    return EXIT_FAILURE;
    } // if(!cin)
    } // for(i)
    // - process the arrays -
    return 0;
    } // main()

    If you have been taught 'new[]/delete[]/pointers', then that may be what your
    instructor is after. Else, the above should do.

    --
    Bob R
    POVrookie
     
    BobR, Nov 27, 2006
    #12
  13. Nutkin

    Marcus Kwok Guest

    <> wrote:
    > #include <map> // to get std::pair


    std::pair is actually in <utility>.

    --
    Marcus Kwok
    Replace 'invalid' with 'net' to reply
     
    Marcus Kwok, Nov 27, 2006
    #13
  14. Nutkin

    kwikius Guest

    Kevin Handy wrote:
    > Nutkin wrote:
    > > Basicly i have to make a program that calculates the distance between x
    > > and y points in 2d space.
    > > the code basicly goes like this
    > >
    > >
    > > 1. User says how many points they have (max of 10)
    > >
    > > 2. User enters points
    > >
    > > 3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    > > between 2 points
    > >
    > > 4. It displays the length between the first and last point.

    >
    > Why bother entering all the data points, when you are
    > only going to display the first and last points entered,
    > ignoring the rest? If you made me enter 1000 points,
    > then ignored all but the first and last entry, I'd
    > probably get pissed off.
    >
    > > My problem is how do i accept the data. im not sure how to vary the
    > > number of inputs or how to declare the variables. like say the user
    > > wants 6 points how do i let the program know only to ask the user for 6
    > > points. and then how do i do the same calculation for each of those
    > > points.

    >
    > Assuming you want the difference between point 1 and
    > last entered point, just enter/store point 1, then loop
    > through additional points (input, calculate, display, repeat).
    > Only need storage for two points at a time (point 1
    > and current point)


    But is it the distance from the first to last point, or the sums of
    the lengths of discrete disconnected lines, or the length of the line
    joining each point to the next?

    The requirements arent clear AFAICS.

    regards
    Andy Little
     
    kwikius, Nov 27, 2006
    #14
  15. Nutkin

    Steve Pope Guest

    BobR <> wrote:

    >
    >You guys (include Steve Pope) are involving way too much complexity (yes,
    >Steve, a pun). You're not trying to hide simplicity from the boss, but, help
    >a starting student.


    >If the OP could use 'vector' (later states (s)he can't), a simple vector of
    >struct would make life easier (in the OPs assignment).
    >
    >// class Point{ public: // same thing
    >struct Point{
    > double x;
    > double y;
    > Point() : x(0), y(0){}
    > };


    So... since the language already has complex<double> built in, so
    how do you figure it is any less complicated to declare your
    new struct "Point"??

    Use what's already there, I say.

    Steve
     
    Steve Pope, Nov 28, 2006
    #15
  16. Nutkin

    Jim Langston Guest

    "Nutkin" <> wrote in message
    news:...
    > Basicly i have to make a program that calculates the distance between x
    > and y points in 2d space.
    > the code basicly goes like this
    >
    >
    > 1. User says how many points they have (max of 10)


    Okay, good. Store this in a variable.

    > 2. User enters points


    Okay, good. Store these values somewhere. A std::vector would be good, but
    if that is beyond you, a dynamic array.

    > 3. Using sqrt( (x2-x1)^2 + (y2-y1)^2) ) It calculates the distance
    > between 2 points


    Which two? You entered 2 to 10 points. All of them to each other? 2-3,
    then 3-4, then 4-5 ?

    > 4. It displays the length between the first and last point.


    Oh, I see. I think you want to total the paths. It's not truely the
    distance between the first point and the last point, but the total of the
    distance with the points inbetween.

    > My problem is how do i accept the data. im not sure how to vary the
    > number of inputs;


    A for loop or while loop works for this.

    > or how to declare the variables. like say the user
    > wants 6 points how do i let the program know only to ask the user for 6
    > points. and then how do i do the same calculation for each of those
    > points.


    A vector or a dynamic array works for this.

    > i tried using a while loop and heres my code so far.
    >
    > #include <iostream>;
    > #include <cmath.h>
    >
    > using namespace std;
    >
    > double length(double xa,double xb,double ya,double yb)
    > {
    > double length=0;
    >
    > length=sqrt(((xb-xa)*(xb-xa))+((yb-ya)*(yb-ya)));
    >
    > return (length);
    >
    > }
    >
    > int main()
    >
    > int points=0;
    > int ans=0;
    > double length(double,double,double,double)
    > double xa=0;
    > double xb=0;
    > double ya=0;
    > double yb=0;
    >
    > cout <<"How many points would you like to input (Max 10)?\n\n";
    > cin >>points;
    >
    > while (points > 1)
    > {
    > cout <<"Please enter an x value\n";
    > cin >>xa;
    > cout <<"Please enter a y value\n";
    > cin >>ya;
    > cout <<"Please enter an x value\n";
    > cin >>xb;
    > cout <<"Please enter a y value\n";
    > cin >>yb;
    >
    > ans=ans+length(xa,xb,ya,yb)
    >
    > points=points-1;
    > }
    >
    > return (0);
    >
    > Im using VC++
    >
    >
    > i know the codes a little crappy but hey thats what help is for right
    > :)


    Well, your program would work with a little modification, but what about now
    you want to know the average of the distances, etc? You are not storing the
    points.

    Two ways, like I said. A dynamic array, or a std::vector. I believe in
    your case a std::vector would be prefered.
    But, what do we push onto the vector? A point has two values, an X and a Y.
    You could use std::pair, but a structure is probably prefered.

    (untested code)

    struct Point2D
    {
    double X;
    double Y;
    };
    std::vector<Point2D> Points;

    Okay, instead of a while loop I would use a for loop.

    for ( int i = 0; i < points; ++i )
    // It is customary to start counting in 0 in C++ because arrays are 0 bound
    {
    std::cout >> "Enter point number:" << i << ":";
    Point2D Point;
    std::cin >> Point.X >> Point.Y;
    // Note, if they entered a bad value, such as "blah" then X and Y
    have
    // bad data. Excersice for the reader to deal with this //
    Points.push_back( Point );
    }

    At this point, if all went well, you have a std::vector of Point2D that
    cointains points number of points. You can access them with subscript
    operator such as:

    Points[0].X
    Points[0].Y
    etc...

    You can also access them using iterators.

    std::vector<Point2D>::iterator it = Points.begin();
    (*it).X
    (*it).Y

    I generally use iterators, but for simplsticy sake, we'll use a for loop
    again.

    double TotalDistance = 0;
    for ( int i = 0; i < points - 1; ++i )
    // I would actually use
    for ( size_t i = 0; i < Points.size() - 1; ++i )
    // Whichever you understand better, but you should get to know both forms.
    {
    TotalDistance += length( Ponnts.X, Points.Y, Points[i+i].X,
    Points[i+1].Y );
    }

    and there's your answer.

    Read through all the replies given you and try to understand all of them.
    If you're going to be using C++ you are going to need to learn the
    containers, such as std::vector.
     
    Jim Langston, Nov 28, 2006
    #16
  17. Nutkin

    BobR Guest

    Steve Pope wrote in message ...
    >BobR wrote:
    >
    >>You guys (include Steve Pope) are involving way too much complexity (yes,
    >>Steve, a pun). You're not trying to hide simplicity from the boss, but,

    help
    >>a starting student.

    >
    >>If the OP could use 'vector' (later states (s)he can't), a simple vector of
    >>struct would make life easier (in the OPs assignment).
    >>
    >>// class Point{ public: // same thing
    >>struct Point{
    >> double x;
    >> double y;
    >> Point() : x(0), y(0){}
    >> };

    >
    >So... since the language already has complex<double> **built in,**


    Nope!

    complex<double> CD;
    // `complex' undeclared (first use this function)
    std::complex<double> CD;
    //`complex' undeclared in namespace `std'

    > so
    >how do you figure it is any less complicated to declare your
    >new struct "Point"??


    No header needed! <G>

    >
    >Use what's already there, I say.
    >Steve


    That's the Point! It is/maybe not there yet for the student just starting
    arrays. Seems to me that 'x, y' is easier than 'real, imag' for a student at
    that stage (assuming (s)he isn't a math major <G>).
    If the instructor won't accept 'vector', 'complex' would probably be
    off-limits also.

    If this were a guy modifying a library for Charles Schwab, I'd say "throw the
    curve ball to him". For this instance, we need to put the ball on the tee and
    teach the person to swing the bat.

    --
    Bob R
    POVrookie
     
    BobR, Nov 28, 2006
    #17
  18. Nutkin

    Steve Pope Guest

    BobR <> wrote:

    >Steve Pope wrote in message ...


    >>So... since the language already has complex<double> **built in,**


    >Nope!
    >
    > complex<double> CD;
    > // `complex' undeclared (first use this function)
    > std::complex<double> CD;
    > //`complex' undeclared in namespace `std'


    #include <complex>

    >>Use what's already there, I say.


    > That's the Point! It is/maybe not there yet for the student
    > just starting arrays.


    It should definitely be there.

    Steve
     
    Steve Pope, Nov 28, 2006
    #18
  19. Nutkin

    BobR Guest

    Steve Pope wrote in message ...
    >BobR wrote:
    >
    >>Steve Pope wrote in message ...

    >
    >>>So... since the language already has complex<double> **built in,**

    >
    >>Nope!
    >> complex<double> CD;
    >> // `complex' undeclared (first use this function)
    >> std::complex<double> CD;
    >> //`complex' undeclared in namespace `std'

    >
    >#include <complex>


    Ah ha, so you admit it wasn't 'built-in'!?! <G>

    [ sorry - the devil made me do it. ]
    --
    Bob R
    POVrookie
     
    BobR, Nov 28, 2006
    #19
  20. On 2006-11-27 20:41, Marcus Kwok wrote:
    > <> wrote:
    >> #include <map> // to get std::pair

    >
    > std::pair is actually in <utility>.


    I've always wondered where it was, but never really bothered since I've
    only seldomn used it outside a map. Thanks.

    --
    Erik Wikström
     
    =?ISO-8859-1?Q?Erik_Wikstr=F6m?=, Nov 28, 2006
    #20
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