Accelerated C + + learning notes and----third Chapter

main contents of this chapter

1. Type definition typedef

2. Local Variables

3. Formatting output initial involvement

4 vector vectors and basic methods

This chapter main program code

1. Calculate the average score

#include <iomanip> #include <iostream> #include <string>using namespace Std;int main () {//Ask for and    Read the student ' s name cout << "Please enter your first name:";    String name;    CIN >> name; cout << "Hello," << name << "!" << endl;//ask for and read the midterm and final grades cout    << "Please enter your midterm and final exam grades:";    Double midterm, final;         CIN >> Midterm >> final;//ask for the homework grades cout << "Enter all your homework grades,"    "followed by end-of-file:";//the number and sum of grades read so far int count = 0; Double sum = 0;//a variable into which to read double x;//invariant://we had read ' count ' grades so far, and//' sum        ' Is the sum of the first ' count ' grades while (CIN >> x) {++count;    sum + = x;    }//Write the result streamsize Prec = Cout.precision (); cout << "Your final grade is" << setprecision (3) << 0.2 * Midterm + 0.4 * Final + 0.4 * sum/count << setprecision (PREC)    << Endl; return 0;}

Results:

2. Calculate the median value of a score

#include <algorithm> #include <iomanip> #include <iostream> #include <string> #include < Vector>using namespace Std;int Main () {//ask for and read the student ' s name cout << "Please enter your first    Name: ";    String name;    CIN >> name; cout << "Hello," << name << "!" << endl;//ask for and read the midterm and final grades cout    << "Please enter your midterm and final exam grades:";    Double midterm, final; CIN >> Midterm >> final;//ask for and read the homework grades cout << ' Enter all your homework grad    ES, "followed by End-of-file:";    Vector<double> homework; Double x;//invariant: ' Homework ' contains all the homework grades read so far while (CIN >> x) HOMEWORK.P Ush_back (x);//Check that the student entered some homework grades#ifdef _msc_ver typedef std::vector<double>::si Ze_type VEC_SZ; #else typedef vector<double>::size_type VEC_SZ; #endif VEC_SZ size = Homework.size ();             if (size = = 0) {cout << Endl << "You must enter your grades."        "Please try again." << Endl;    return 1;     }//sort the Grades sort (Homework.begin (), Homework.end ());//Compute the median homework grade VEC_SZ mid = SIZE/2;    Double median; Median = size% 2 = = 0? (Homework[mid] + homework[mid-1])/2:homework[mid];//compute and write the final grade streamsize Prec    = Cout.precision ();         cout << "Your final grade is" << setprecision (3) << 0.2 * Midterm + 0.4 * final + 0.4 * Median    << setprecision (PREC) << Endl; return 0;}

Results:

Exercise Answer

3.2

#include <algorithm> #include <iostream> #include <vector>using namespace Std;int main () {vector<    int> integers;    cout << "integers:";    int x;    while (CIN >> x) integers.push_back (x);        if (integers.size () = = 0) {cout << endl << "No integers!" << Endl;    return 1;    } sort (Integers.rbegin (), Integers.rend ());    typedef vector<int>::size_type VEC_SZ;    cout << "1st quartile" << Endl;    for (VEC_SZ i = 0; i < integers.size ()/4; ++i) cout << integers[i] << Endl;    cout << "2nd quartile" << Endl;    for (VEC_SZ i = integers.size ()/4; I < integers.size ()/2; ++i) cout << integers[i] << Endl;    cout << "3rd quartile" << Endl;    for (VEC_SZ i = integers.size ()/2; I < integers.size () * 3/4; ++i) cout << integers[i] << Endl;    cout << "4th quartile" << Endl; for (VEC_SZi = integers.size () * 3/4; I < integers.size ();    ++i) cout << integers[i] << Endl; return 0;}

Results:

3.3

#include <iostream> #include <string> #include <vector>using namespace Std;int main () {    typedef Vector<string>::size_type VEC_SZ;    vector<string> words;    Vector<int> counts;    cout << "Words:";    string S;    while (CIN >> s)    {        bool found = false;        for (VEC_SZ i = 0; i < words.size (); ++i)        {            if (s = = Words[i])            {                ++counts[i];                Found = true;            }        }        if (!found)        {            words.push_back (s);            Counts.push_back (1);        }    }    for (VEC_SZ i = 0; i < words.size (); ++i)        cout << words[i] << "appeared" << Counts[i] << "Times" << Endl;    return 0;}

Results:

3.4

#include <iostream> #include <string>using namespace Std;int main () {    typedef string::size_type STR_SZ;    string Longest;    STR_SZ longest_length = 0;    string shortest;    STR_SZ shortest_length = 0;    cout << "Words:";    string S;    while (CIN >> s)    {        if (longest_length = = 0 | | s.size () > Longest_length)        {            longest = s;            Longest_length = S.size ();        }        if (Shortest_length = = 0 | | s.size () < Shortest_length)        {            shortest = s;            Shortest_length = S.size ();        }    }    cout << "Longest:" << longest << Endl;    cout << "Shortest:" << shortest << Endl;    return 0;}

3.5

#include <iomanip> #include <iostream> #include <string> #include <vector>using namespace std;#    Define Num_homework 2using Std::vector;int main () {vector<string> names;    Vector<double> Final_grades;    bool done = false;        while (!done) {//ask for and read the student's name cout << "Please enter your first name:";        String name;        CIN >> name;        cout << "Hello," << name << "!" << Endl;        Names.push_back (name);         Ask for and read the midterm and final grades cout << "Please enter your midterm and final exam grades:";        Double midterm, final;        CIN >> midterm >> final; Ask for the homework grades cout << "Enter Both your homework grades," "followed by End-of-fi        Le: ";        He number and sum of grades read so far int count = 0;        Double sum = 0; A variable into which toRead Double X;        Invariant://We have read ' count ' grades so far, and//' sum ' is the sum of the first ' count ' grades            while (Count < num_homework) {++count;            CIN >> X;        sum + = x;        } Double Final_grade = 0.2 * Midterm + 0.4 * Final + 0.4 * sum/count;        Final_grades.push_back (Final_grade); cout << "More? (y/n)        ";        string S;        Cin >> S;    if (s! = "Y") done = true; } for (Vector<string>::size_type i = 0; i < names.size (); ++i) {//write the result Streamsi        Ze prec = cout.precision ();             cout << names[i] << "' s final grade is" << setprecision (3) << Final_grades[i]    << setprecision (PREC) << Endl; } return 0;}

3.6

#include <iomanip> #ifndef __gnuc__#include <ios> #endif # include <iostream> #include <string>    Using namespace Std;int Main () {//ask for and read the student's name cout << "Please enter your first name:";    String name;    CIN >> name; cout << "Hello," << name << "!" << endl;//ask for and read the midterm and final grades cout    << "Please enter your midterm and final exam grades:";    Double midterm, final;         CIN >> Midterm >> final;//ask for the homework grades cout << "Enter all your homework grades,"    "followed by end-of-file:";//the number and sum of grades read so far int count = 0; Double sum = 0;//a variable into which to read double x;//invariant://we had read ' count ' grades so far, and//' sum        ' Is the sum of the first ' count ' grades while (CIN >> x) {++count;    sum + = x; } Double Homework_grade = (Count > 0)? sum/count:0.0;//write the result streamsize Prec = Cout.precision (); cout << "Your final grade is" << setprecision (3) << 0.2 * Midterm + 0.4 * Final + 0.4 * homewor    K_grade << setprecision (prec) << Endl; return 0;}

Accelerated C + + learning notes and----third Chapter