write random hour + temperature pairs

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 10 Exercise 2
Using std_lib_facilities.h by Bjarne Stroustrup.

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PPP
// Chapter 10 Exercise 2

#include "std_lib_facilities.h"

struct Reading {
int hour;
double temperature;
};

ostream& operator<<(ostream& os, Reading& _temps) {
os << _temps.hour << " " << _temps.temperature << endl;
return os;
}

vector<Reading> temps;

string oname = "output/raw_temps.txt";
ofstream ost(oname);

void fill_vector(vector<Reading>& _temps) {
cout << "Generating Data." << endl;
int h;
double t;
int temp_hour = 0;
for (int i = 0; i < 50; i++) {
if (!(i % 24)) {
temp_hour = 0;
}
h = temp_hour;
t = randint(90);
_temps.push_back(Reading{ h, t });
temp_hour++;
}
}

void write_file(vector<Reading>& _temps) {
cout << "Writing File." << endl;
for (int i = 0; i < temps.size(); i++) {
ost << _temps[i];
}
cout << "Done!" << endl;
}

int main()
try
{

fill_vector(temps);
write_file(temps);

keep_window_open();
}
catch(runtime_error e) {
cout << e.what() << endl;
keep_window_open();
}
catch (…) {
cout << "Exiting" << endl;
keep_window_open();
}
[/code]

Output:
Generating Data.
Writing File.
Done!
Please enter a character to exit

Output-File raw_temps.txt:
0 78
1 14
2 1
3 15
4 72
5 20
6 65
7 54
8 49
9 67
10 48
11 73
12 67
13 49
14 20
15 42
16 76
17 38
18 36
19 40
20 15
21 87
22 16
23 51
0 34
1 63
2 37
3 48
4 79
5 41
6 60
7 21
8 15
9 51
10 1
11 41
12 84
13 13
14 79
15 38
16 0
17 16
18 86
19 88
20 76
21 50
22 73
23 77
0 74
1 44