area function debugging

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 5 Try This page 146
Using std_lib_facilities.h by Bjarne Stroustrup.

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PP
// Chapter 5 Try This page 146

#include "std_lib_facilities.h"

int area(int length, int width) {
if (length <= 0 || width <= 0) {
return -1;}
return length * width;
}

int framed_area(int x, int y) {
constexpr int frame_width = 2;
if (x – frame_width <= 0 || y – frame_width <= 0) {
error("non-positive area() argument called by framed_area()");
}
return area(x – frame_width, y – frame_width);
}

double f(int x, int y, int z) {
int area1 = area(x, y);
if (area1 <= 0) {
error("non-positive area");
}
cout << "area1 = " << area1 << ‘\n’;

if (x > 2 && y > 2 && z > 2) {
int area2 = framed_area(3, z);
int area3 = framed_area(y, z);
double ratio = double(area1) / double(area3);

cout << "area2 = " << area2 << ‘\n’;
cout << "area3 = " << area3 << ‘\n’;
cout << "ratio = " << ratio << ‘\n’;
return 0;
}
else {
error("Input for x, y and z must be larger than frame width");
return -1;
}
}

int main()
try
{
f(3, 3, 3);
keep_window_open();
}
catch (exception& e) {
cerr << "error: " << e.what() << ‘\n’;
keep_window_open();
return 1;
}
catch (…) {
cerr << "Unknown exception!\n";
keep_window_open();
return 2;
}
[/code]

Output:
area1 = 9
area2 = 1
area3 = 1
ratio = 9