Add a simple class stack, and example

data_structure/stk/main.cpp

@@ -0,0 +1,55 @@
+/*
+ * This program reads a data file consisting of students' GPAs
+ * followed by their names. The program then prints the highest
+ * GPA and the names of the students with the highest GPA.
+ * It uses stack to store the names of the students
+ * Run:
+ *     make all
+ *     ./main student.txt
+ ************************************************************
+ * */
+#include <iostream>
+#include <iomanip>
+#include <fstream>
+#include <string>
+#include <assert.h>
+
+#include "stack.h"
+#include "stack.cpp"
+
+using namespace std;
+
+int main(int argc, char * argv[]) {
+    double GPA;
+    double highestGPA;
+    string name;
+
+    assert(argc == 2);
+    ifstream infile;
+    stack<string> stk;
+
+    infile.open(argv[1]);
+    cout << fixed << showpoint;
+    cout << setprecision(2);
+    infile >> GPA >> name;
+    highestGPA = GPA;
+
+    while (infile) {
+        if (GPA > highestGPA) {
+            stk.clear();
+            stk.push(name);
+            highestGPA = GPA;
+        } else if (GPA == highestGPA) {
+            stk.push(name);
+        }
+        infile >> GPA >> name;
+    }
+    cout << "Highest GPA: " << highestGPA <<endl;
+    cout << "Students the highest GPA are: " << endl;
+    while (!stk.isEmptyStack()) {
+        cout << stk.top() << endl;
+        stk.pop();
+    }
+    cout << endl;
+    return 0;
+}