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ICOM 4015 Advanced Programming

This lecture covers the concept of procedural arguments and top-down stepwise refinement in programming, using integration functions as examples.

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ICOM 4015 Advanced Programming

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  1. ICOM 4015 Advanced Programming Lecture 5 Procedural Abstraction III Reading: Chapter 3 Prof. Bienvenido Velez ICOM 4015

  2. Administrivia • Program 0 (Due Feb 16) • Office Hours • Lunes y Miércoles 10:30-12:30 • or by appointment • Office T-212 • Email • Make sure your email address is correct and functional • Check your email daily! ICOM 4015

  3. Procedural Abstraction III Outline • Procedural arguments • Top-down stepwise refinement ICOM 4015

  4. IntegrationWithout Procedural Arguments #include <iostream> // Forward definitions double integrateSqr(double a, double b, double n); double integrateCube(double a, double b, double n); int main() { cout << "Integral of x^2 in [0,1] = " << integrateSqr(0.0, 1.0, 10000) << endl; cout << "Integral of x^3 in [0,1] = " << integrateCube(0.0, 1.0, 10000) << endl; } double integrateSqr(double a, double b, double n) { double delta = (b-a) / double(n); double sum = 0.0; for (int i=0; i<n; i++) { float x = a + delta * i; sum += x * x * delta; } return sum; } double integrateCube(double a, double b, double n) { double delta = (b-a) / double(n); double sum = 0.0; for (int i=0; i<n; i++) { float x = a + delta * i; sum += x * x * x * delta; } return sum; } [bvelez@amadeus] ~/icom4015/lec05 >> example2 Integral of x^2 in [0,1] = 0.333283 Integral of x^3 in [0,1] = 0.24995 [bvelez@amadeus] ~/icom4015/lec05 >> ICOM 4015

  5. Example 3 IntegrationWith Procedural Arguments #include <iostream> // Forward definitions double integrate(double a, double b, double n, double f(double x)); double cube(double x); double sqr(double x); int main() { cout << "Integral of x^2 in [0,1] = " << integrate(0.0, 1.0, 10000, sqr) << endl; cout << "Integral of x^3 in [0,1] = " << integrate(0.0, 1.0, 10000, cube) << endl; } double integrate(double a, double b, double n, double f(double x)) { double delta = (b-a) / double(n); double sum = 0.0; for (int i=0; i<n; i++) { sum += f(a + delta * i) * delta; } return sum; } double cube(double x) { return x * x * x; } double sqr(double x) { return x * x; } [bvelez@amadeus] ~/icom4015/lec05 >> example2 Integral of x^2 in [0,1] = 0.333283 Integral of x^3 in [0,1] = 0.24995 [bvelez@amadeus] ~/icom4015/lec05 >> ICOM 4015

  6. Step 0 - Outline // top-down.cc // Computes weighted average score of grades. Grades // include two assignments two midterm exams and one final exam. // All grades are input from standard input, but the weights of // each type of grade are hard coded. // C header files extern "C" { } // Standard C++ header files #include <iostream> // My own C++ header files // Macro definitions // Forward definitions of auxiliary functions // Global declarations // Main function int main() { // Read assignment grades // Read exam grades // Read final exam grade // Calculate average // Print report return 0; } // Auxiliary functions ICOM 4015

  7. Step 1 – Code + Stubs int main() { float assignment1, assignment2; float exam1, exam2; float finalExam; readAssignmentGrades(assignment1, assignment2); readExamGrades(exam1, exam2); readFinalGrade(finalExam); float avg; avg = calculateAverage(assignment1, assignment2, exam1, exam2, finalExam); printReport(assignment1, assignment2, exam1, exam2, finalExam, avg); return 0; } // Auxiliary functions void readAssignmentGrades(float& assignment1, float& assignment2) {} void readExamGrades(float& ex1, float& ex2) {} void readFinalGrade(float& final) {} float calculateAverage(float assignment1, float assignment2, float exam1, float exam2, float finalExam) {} void printReport(float assignment1, float assignment2, float exam1, float exam2, float finalExam, float average) {} ICOM 4015

  8. Step 2 - Refine // Auxiliary functions void readAssignmentGrades(float& assignment1, float& assignment2) { // Read a float in [0,100] into assignment1 // Read a float in [0,100] into assignment2 } void readExamGrades(float& ex1, float& ex2) { // Read a float in [0,100] into ex1 // Read a float in [0,100] into ex2 } void readFinalGrade(float& final) { // Read a float in [0,100] into final } float calculateAverage(float assignment1, float assignment2, float exam1, float exam2, float finalExam) { // Calculate assignments average // Calculate exams average // Calculate weighted average } void printReport(float assignment1, float assignment2, float exam1, float exam2, float finalExam, float average) { // print assignment grades // print exam grades // print final exam grades // print weighted average } ICOM 4015

  9. Top-down stepwise refinement cycle outline refine code + stubs ICOM 4015

  10. Summary of Concepts • Procedural arguments • Allow abstraction over processes and functions • Top-Down design / stepwise refinement • A cyclic development technique • Each cycle adds a level of detail to the code • We have a functioning (although incomplete) program after every iteration of the process ICOM 4015

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