C++ Save a Struct String into A Text File - c++

Question

In my program, I save high scores along with a time in minutes and seconds. In my code, I currently store this as two ints in a struct called highscore. However, this is a little tedious when it comes to formatting when I display the output. I want to display the times as 12:02 not 12:2. I have a variable already made called string clock throughout my game, it is already formatted with the colon, all I want to do is add that inside my text file.
How can I refactor my code to have a single variable for the timestamp, which will be correctly formatted? I want to be able to write my data into the file by directly calling the structure.
// Used for Highscores
struct highscore
{
char name[10];
int zombiesKilled;
// I would like these to be a single variable
int clockMin;
int clockSec;
char Date[10];
};
// I write the data like this:
highscore data;
// ...
data[playerScore].clockMin = clockData.minutes;
data[playerScore].clockSec = clockData.seconds;
streaming = fopen( "Highscores.dat", "wb" );
fwrite( data, sizeof(data), 1 , streaming);
// ...

Answer 1

It seems that you want to simply just write a C-string or std::string to a file using C's fwrite() function.
This should be quite easy, given that your C-string is in ASCII-conforming format (no Unicode funny business):
//It appears you want to use C-style file I/O
FILE* file = NULL;
fopen("Highscores.dat", "wb");
//std::string has an internal C-string that you can access
std::string str = "01:00";
fwrite(str.c_str(), sizeof(char), sizeof(str.c_str()), file);
//You can also do this with regular C strings if you know the size.
We can also choose to try and use C++-style file I/O for cleaner interfaces.
#include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
int main() {
std::string str = "00:11";
std::ofstream file("example.txt");
if (file.good()) {
file << str;
std::cout << "Wrote line to file example.txt.\n";
}
file.close();
//Let's check if we actually wrote the file.
std::ifstream read("example.txt");
std::string buffer;
if (read.good())
std::cout << "Opened example.txt.\n";
while(std::getline(read, buffer)) {
std::cout << buffer;
}
return 0;
}
Additionally, there are data types in <chrono> that can prove quite helpful for times like there.
If you want to be able to do this:
file << data_struct;
then it would make sense for you to create an operator overload for std::ostream.

Answer 2

You can experiment with time functions. And reading/writing structures.
The right way however is to use c++ basic file storage instead of dumping binar data.
struct highscore
{
char name[10];
int n;
std::time_t dateTime;
};
int main()
{
int total_seconds = 61;
char buf[50];
sprintf(buf, "minutes:seconds=> %02d:%02d", total_seconds / 60, total_seconds % 60);
cout << buf << endl;
std::time_t timeNow = std::time(NULL);
std::tm timeFormat = *std::localtime(&timeNow);
cout << "Current date/time " << std::put_time(&timeFormat, "%c %Z") << endl;
highscore data;
//write data:
{
FILE *streaming = fopen("Highscores.dat", "wb");
strcpy(data.name, "name1");
data.n = 1;
data.dateTime = std::time(NULL);
fwrite(&data, sizeof(data), 1, streaming);
strcpy(data.name, "name2");
data.n = 2;
data.dateTime = std::time(NULL);
fwrite(&data, sizeof(data), 1, streaming);
fclose(streaming);
}
//read data:
{
FILE *streaming = fopen("Highscores.dat", "rb");
fread(&data, sizeof(data), 1, streaming);
cout << "reading:\n";
cout << data.name << endl;
cout << data.n << endl;
timeFormat = *std::localtime(&data.dateTime);
cout << std::put_time(&timeFormat, "%c %Z") << endl;
cout << endl;
fread(&data, sizeof(data), 1, streaming);
cout << "reading:\n";
cout << data.name << endl;
cout << data.n << endl;
timeFormat = *std::localtime(&data.dateTime);
cout << std::put_time(&timeFormat, "%c %Z") << endl;
cout << endl;
fclose(streaming);
}
return 0;
}