I have a Stock class in which one of the members is a string which maximum length will be at most 6 chars (stock tickers in the NASDAQ cannot be longer than 5 characters plus the added Q if they were to go bankrupt). However, since the NASDAQ alone has about 3500 stocks I would like to use as little data as possible when making a Stock object. std::string allocates more space than I need for its contents and I am trying to reduce memory consumption. Would the extra allocated memory that std::string uses affect the performance of my program at all?
In the following code it shows that the member variable symbol has a size of 15 even though there are only 4 chars in it. Can I restrict the string size to 6 bytes using str.reserve inside the class before the initialization, or should I instantiate the object then call symbol.resize(6) to ensure there are only 6 bytes being used?
#include <iostream>
#include <string>
using namespace std;
class Stock
{
public:
Stock(string s, double o, double c, unsigned int v)
: symbol(s), open(o), close(c), volume(v) {};
~Stock() = default;
string symbol;
double open;
double close;
unsigned int volume;
};
int main() {
Stock AAPL("AAPL", 267.48, 270.71, 26547493);
cout << AAPL.symbol.capacity() << endl;
cout << AAPL.symbol.size() << endl;
return 0;
}
From reading the answer to this question STD::string as a Member Parameter for Dynamically Allocated Objects it seems that this extra allocated space that std::string uses should not interfere at all with the memory of my program, but I am not 100% sure and I would prefer if someone could corroborate my assumption.
