Looping over all files in a folder to proceed script - c++

Question

I attached a simplified C++ code which read a data from a file and get average over the vector and save the output into csv. file. My problem is I have 100 files which named test1.csv, test2.csv,... test100.csv and do the same job for 100 files recursively and want to save the each output as result1.cvs, result2.csv, ... result100.csv respectively.
Frankly, I am a frequent use for Matlab/R and with that this loop is easy to implement but as a beginner for C++, I am puzzling from the beginning.
Each file has one vector of different historical stock price data with same length stock prices (like apple, microsoft, IBM, GM....).
Following is simplified code for your reference but actual code is very complicated one which will generate 25000*30000 matrix output,each.
Sample data in the data file is like;
45.78
67.90
87.12
34.89
34.60
29.98
......
Thanks you for your help in advance.
#include <fstream>
#include <iostream>
int main() {
//std::ifstream infile ("E:\\DATA\\test1.txt");
std::ifstream infile ("E:\\DATA\\test1.csv");
float num;
float total = 0.0f;
unsigned int count = 0;
// While infile successfully extracted numbers from the stream
while(infile >> num) {
total += num;
++count;
}
// don't need the file anymore, close it
infile.close();
// test to see if anything was read (prevent divide by 0)
if (!count) {
std::cerr << "Couldn't read any numbers!" << std::endl;
return 1;
}
// give the average
std::cout << "The average was: " << total/count << std::endl;
std::cout << "The sum was: " << total << std::endl;
std::cout << "The length was: " << count << std::endl;
// pause the console
// std::cin.sync();
//std::cin.get();
std::ofstream myfile;
myfile.open ("E:\\DATA\\result1.csv"); //check!!!!
myfile<<total/count<<","; //Add "," for csc format
myfile.close();
std::cout << "average was sucessfully saved !!!! /n";
return 0;
}
//source http://www.cplusplus.com/forum/general/124221/

Answer 1

It sounds like it would be easiest to run this code in a for loop, updating the filename strings with each iteration. For example:
#include <string>
#include <iostream>
#include <fstream>
int main() {
for (int i = 1; i <= 100; i++) {
std::string inFile;
std::string outFile;
// Add the prefix to the filename
inFile.append("test");
outFile.append("result");
// Add the number to the filename
inFile.append(std::to_string(i));
outFile.append(std::to_string(i));
// Add the suffix to the filename
inFile.append(".csv");
outFile.append(".csv");
// std::cout << inFile << std::endl;
// std::cout << outFile << std::endl;
std::ifstream fin;
std::ofstream fout;
fin.open(inFile);
fout.open(outFile);
// TODO:Use fin and fout
}
return 0;
}
You could also do this with character arrays (C-Strings) if you're more comfortable with that, or if you only have an older version of C++, but the concept is the same. Create a string that concatenates the file prefix, the file number, and the file suffix, and open that instead of hard-coding the filename.