Chapter03

Author: 007kevin

Chapter03/3-3.cpp

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+/* Excercise 3-3
+ * Write a program to count how many times each distinct word
+ * appears appears in its input 
+ */
+
+#include <iostream>
+#include <algorithm>
+#include <vector>
+
+using namespace std;
+
+int main(){
+    vector<string> strlist;
+    vector<string>::size_type count = 0;
+    string x;
+
+    //invariant: count is the number of unique strings in the vector
+    while (cin >> x){
+        if (count == 0){
+            strlist.push_back(x);
+            ++count;
+        }
+        else{
+            int i;
+            //invariant: have compared i strings in the vector
+            for (i = 0; i < count; i++)
+                if (strlist[i] == x)
+                    break;
+            if (i == count){
+                 strlist.push_back(x);
+                 ++count;
+            }
+        }
+    }    
+    cout << count << " unique values found." << endl;
+
+    return 0;
+}

Chapter03/3-4.cpp

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+/* Exercise 3-4
+ * Write a program to report the length of the longest and 
+ * shortest string in its input
+ */
+
+#include <iostream>
+#include <string>
+
+int main(){
+    std::string x, longest, shortest;
+    longest = shortest = "";
+    std::string::size_type llength, slength;
+    llength = slength = 0;
+
+    
+    while (std::cin >> x){
+        if (x.size() > longest.size())
+            llength = (longest = x).size();
+
+        if (shortest == "" || x.size() < shortest.size())
+            slength = (shortest = x).size();
+                
+    }
+    
+    /* note: this will print only the first encounters of 
+     * the longest and shortest strings
+     */
+    std::cout << "The longest string and size: " << longest
+                << " " << llength << std::endl;
+    std::cout << "The shortest string and size: " << shortest 
+                << " " << slength << std::endl;
+    return 0;
+}

Chapter03/3-5.cpp

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+/* Exercise 3-5
+ * Write a program that will keep track of grades of several 
+ * students at once. The program could keep two vectors in sync: 
+ * The first should hold the student's names, and the second the final
+ * grades that can be computed as input read. For now, you should
+ * assume a fixed number of homework grades
+ */
+
+#include <iostream>
+#include <ios> /* to define streamsize */
+#include <iomanip> /* for the output manipulator setprecision */
+#include <string>
+#include <vector>
+
+using std::cin;     using std::setprecision;
+using std::cout;    using std::string;
+using std::endl;    using std::vector;
+using std::streamsize;
+
+#define NUM_HW 3
+
+int main(void){
+    vector<string> nameList;
+    vector<double> gradeList;
+    bool done = false;
+
+    while (!done){
+        //ask for student's name
+        cout << "Please enter your first name: ";
+        string name;
+        cin >> name;
+        cout << "Hello, " << name << "!" << endl;
+        nameList.push_back(name);
+
+        //ask for midterm and final exam grades
+        cout << "Please enter your midterm and final grades: ";
+        double midterm, final;
+        cin >> midterm >> final;
+
+        //ask for and read homework grades
+        cout << "Enter all your homework grades: ";
+        vector<double> homework;
+        // a variable into which to read
+        double x;
+        int count = 0;
+        double sum = 0;
+        while (count < NUM_HW){
+            cin >> x;
+            sum += x;
+            count++;
+        }
+        //calculate final grades to be inputted into the gradeList
+        double finalgrade = 0.2 * midterm + 0.4 * final + 0.4 * sum/count;
+        gradeList.push_back(finalgrade);
+
+        cout << "More students? (Y/N) ";
+        string s;
+        cin >> s;
+        if (s != "Y")
+            done = true;
+    }
+
+    vector<string>::size_type size = nameList.size();
+    int i;
+    for (i = 0; i < size; i++){
+        streamsize prec = cout.precision();
+        cout << "Student: " << nameList[i] << ", " << "Grade: " << setprecision(3) << gradeList[i] << setprecision(prec) << endl;
+    }
+
+
+    return 0;
+}