// Append counter & error info:
ostringstream out;
out << buf << " // (" << ++counter << ") "
<< "Chapter " << CHAP
<< " File: " << FNAME
<< " Line " << linecount << endl;
edited << out.str();
errlines << out.str(); // Append error file
}
else
edited << buf << "\n"; // Just copy
linecount++;
}
}
void saveFiles() {
ofstream outfile(FNAME.c_str()); // Overwrites
assure(outfile, FNAME.c_str());
outfile << edited.rdbuf();
ofstream count(ERRNUM.c_str()); // Overwrites
assure(count, ERRNUM.c_str());
count << counter; // Save new counter
}
};
int main(int argc, char* argv[]) {
const string ERRCOUNT("../errnum.txt"),
ERRFILE("../errlines.txt");
requireMinArgs(argc, 1, usage.c_str());
if(argv[1][0] == '/' || argv[1][0] == '-') {
// Allow for other switches:
switch(argv[1][1]) {
case 'r': case 'R':
cout << "reset counter" << endl;
remove(ERRCOUNT.c_str()); // Delete files
remove(ERRFILE.c_str());
return 0;
default:
cerr << usage << endl;
return 1;
}
}
if (argc == 3) {
Showerr s(argv[1], ERRCOUNT, ERRFILE, atoi(argv[2]));
s.replaceErrors();
s.saveFiles();
}
} ///:~
You can replace the marker with one of your choice.
Each file is read a line at a time, and each line is searched for the marker appearing at the head of the line; the line is modified and put into the error line list and into the string stream, edited. When the whole file is processed, it is closed (by reaching the end of a scope), it is reopened as an output file, and edited is poured into the file. Also notice the counter is saved in an external file. The next time this program is invoked, it continues to sequence the counter.
This example shows an approach you might take to log data to disk and later retrieve it for processing. It is meant to produce a temperature-depth profile of the ocean at various points. To hold the data, a class is used:.
//: C04:DataLogger.h
// Datalogger record layout
#ifndef DATALOG_H
#define DATALOG_H
#include
#include
#include
using std::ostream;
struct Coord {
int deg, min, sec;
Coord(int d = 0, int m = 0, int s = 0)
: deg(d), min(m), sec(s) {}
std::string toString() const;
};
ostream& operator<<(ostream&, const Coord&);
class DataPoint {
std::time_t timestamp; // Time & day
Coord latitude, longitude;
double depth, temperature;
public:
DataPoint(std::time_t ts, const Coord& lat,
const Coord& lon, double dep, double temp)
: timestamp(ts), latitude(lat), longitude(lon),
depth(dep), temperature(temp) {}
DataPoint() : timestamp(0), depth(0), temperature(0) {}
friend ostream& operator<<(ostream&, const DataPoint&);
};
#endif // DATALOG_H ///:~
A DataPoint consists of a time stamp, which is stored as a time_t value as defined in
//: C04:DataLogger.cpp {O}
// Datapoint implementations
#include "DataLogger.h"
#include
#include
#include
#include
using namespace std;
ostream& operator<<(ostream& os, const Coord& c) {
return os << c.deg << '*' << c.min << '\''
<< c.sec << '"';
}
string Coord::toString() const {
ostringstream os;
os << *this;
return os.str();
}
ostream& operator<<(ostream& os, const DataPoint& d) {
os.setf(ios::fixed, ios::floatfield);
char fillc = os.fill('0'); // Pad on left with '0'
tm* tdata = localtime(&d.timestamp);
os << setw(2) << tdata->tm_mon + 1 << '\\'
<< setw(2) << tdata->tm_mday << '\\'
<< setw(2) << tdata->tm_year+1900 << ' '
<< setw(2) << tdata->tm_hour << ':'
<< setw(2) << tdata->tm_min << ':'
<< setw(2) << tdata->tm_sec;
os.fill(' '); // Pad on left with ' '
streamsize prec = os.precision(4);
os << " Lat:" << setw(9) << d.latitude.toString()
<< ", Long:" << setw(9) << d.longitude.toString()
<< ", depth:" << setw(9) << d.depth
<< ", temp:" << setw(9) << d.temperature;
os.fill(fillc);
os.precision(prec);
return os;
} ///:~
The Coord::toString( ) function is necessary because the DataPoint inserter calls setw( ) before it prints the latitude and longitude. If we used the stream inserter for Coord instead, the width would only apply to the first insertion (that is, to Coord::deg), since width changes are always reset immediately. The call to setf( ) causes the floating-point output to be fixed-precision, and precision( ) sets the number of decimal places to four. Notice how we restore the fill character and precision to whatever they were before the inserter was called.
To get the values from the time encoding stored in DataPoint::timestamp, we call the function std::localtime( ), which returns a static pointer to a tm object. The tm struct has the following layout:
struct tm {
int tm_sec; // 0-59 seconds
int tm_min; // 0-59 minutes
int tm_hour; // 0-23 hours
int tm_mday; // Day of month
int tm_mon; // 0-11 months
int tm_year; // Years since 1900
int tm_wday; // Sunday == 0, etc.
int tm_yday; // 0-365 day of year
int tm_isdst; // Daylight savings?
};
