CSE 109 Test 2  Wednesday  11 April 2008
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NAME_______________________________________________________________
1.  Consider the ADT for an interval of some type. An interval has a lower
    and an upper bound.  An object is in the interval if and only if its
    value is between the two bounds (including the two bounds). Write a
    template, Interval, that implements this ADT. It need only have those
    methods necessary for the code below to compile and produce the indicated
    results.

    Interval<double> x(2.1,4);   //all t such that 2.1<=t<=4
    cout<<x<<endl;  //OUTPUT: [ 2.1, 4]
    x.shift(3.1);
    cout<<x<<endl;  //OUTPUT: [ 5.2, 7.1]
    for(int j=4;j<10;j+=2)
     if(x.contains(j))
      cout<<"yes ";
     else
      cout<<"no ";    //OUTPUT:  no yes no
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#include <iostream>
using namespace std;

template <class A>
  class Interval{
  public:
    Interval(const A&lo,const A &h);
    Interval & shift(const A & delta);
    bool contains(const A &a)const;
    template <class X>
    friend ostream & operator<<(ostream &out,const Interval<X> &b);
  private:
    A low,high;
    static void check(bool b,char *mess);
  };

  template <class A>
    Interval<A>::Interval(const A&lo,const A&h):low(lo),high(h){
    check(lo<=h,"Illegal bounds");
  }

    template <class A>
     Interval<A> & Interval<A>:: shift(const A & delta){
      low+=delta;
      high+=delta;
      return *this;
    }

  template <class A>
    bool Interval<A>::contains(const A &a)const{
    return a>=low && a<=high;
  }

  template <class A>
    void Interval<A>::check(bool b,char *mess){
    if(!b){
      cerr<<"ERROR[Interval] :"<<mess<<endl;
      exit(1);
    }
  }

template <class X>
ostream & operator<<(ostream &out,const Interval<X> &b){
  out<<"[ "<<b.low<<", "<<b.high<<"]";
  return out;
}
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2. Below is my start on the declaration of the class Word.  Provide the
declaration and definition for the operator '+' so that the following code
produces the indicated output.  ('+' implements concatenation)
class Word
{public:
  public static int LENGTHMAX=12;
  Word(char *st="");
  const Word & operator=(const Word &w);
  friend ostream & operator <<(ostream &out,const Word &w);
 private:
  char str[LENGTHMAX+1];  //see below for the version actually used
  static void check(bool ok,char *mess);
};
   Word a;
   a="Hello";
   a=a+", World";
   cout<<a<<endl; //OUTPUT: Hello, World
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  friend Word operator+(const Word &a,const Word&b);

Word operator+(const Word &a,const Word&b){
  a.check((int)(strlen(a.wd)+strlen(b.wd))<=a.LENGTHMAX,"String too long");
  Word temp(a);
  strcat(temp.wd,b.wd);
  return temp;
}
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(another version)
2. Below is my start on the declaration of the class Word.  Provide the
declaration and definition for the operator '+' so that the following code
produces the indicated output.  ('+' implements concatenation)
class Word
{public:
  public static int LENGTHMAX=12;
  Word(char *st="");
  const Word & operator=(const Word &w);
  friend ostream & operator <<(ostream &out,const Word &w);
 private:
  char *str;
  static void check(bool ok,char *mess);
};
   Word a;
   a="Hello";
   a=a+"World";
   cout<<a<<endl; //OUTPUT: Hello, World
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  friend Word operator+(const Word &a,const Word&b);

Word operator+(const Word &a,const Word&b){
  Word temp;
  delete []temp.str;
  temp.str=new char[strlen(a.str)+strlen(b.str)+1];
  check(temp.str!=NULL,"('+') heap overflow");
  strcpy(temp.str,a.str);
  strcpy(temp.str,b.str);
  return temp;
}
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3.  Write a program whose sole purpose is to count the number of characters
in each of the arguments entered in the command line, including the call to
the program itself.  For example, if the call is
   a.out one two three
the program should print out (counting 5 for 'a.out', 3 for 'one', etc.)
   The number of characters is 16.
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#include <iostream>
using namespace std;

int main(int ct,char **mess){
  int count,loc;
  count=0;
  for(int j=0; j<ct;j++){//could replace for loop with two lines below program
    loc=0;
    while(mess[j][loc]!='\0'){
      loc++;
    }
    count+=loc;
  }
  cout<<"The number of characters is "<<count<<endl;
}

OR  for(int j=0;j<ct;j++)
     count+=strlen(mess[j]);
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4.  Write SML code that would have the same effect as the YAPL program below.
    (Recall the SML operators:  10(read), 11(write), 20(load), 21(store),
    30(add), 31(subtract), 32(divide), 33(multiply), 40(branch), 41(branch
    if negative), 42(branch if zero), 43(halt).)

      read x
      goto 100 if x<=3
      write 1
  100      halt
      end
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10007         0 read
20007         1 load x
31008         2 sub 3
41006         3
42006         4
11009         5
43000      6
0          7
3          8
1          9
END
2
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