Converting data from CSV string to float

Question

How do I convert a string from my CSV file (excel worksheet) to a float value? Suppose that my CSV sheet contains:

0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1

and my code so far is:

#include <iostream>
#include <fstream>
#include <sstream>
#include <string>

using namespace std;

int main()
{
    ifstream myfile("data1.csv");
    string line;
    getline(myfile,line,',');
    cout << line;
}

I am able to obtain line as a string, specifically type Ss but I need to convert the line into a float. How do I do that?

First Google hit gives header-only library github.com/ben-strasser/fast-cpp-csv-parser. Or check this SO question stackoverflow.com/questions/1120140/… — Petr Javorik
– Petr Javorik, Commented Jul 27, 2018 at 9:16

Swordfish · Accepted Answer · 2018-07-27 09:27:19Z

1

Keeping it plain C++ without additional libraries: Don't read strings, read floats:

float value;
char delim;
if( !( is >> value >> delim ) && ( delim == ',' || delim == '\n' ) )
    // format error

edited Jul 27, 2018 at 9:27

answered Jul 27, 2018 at 9:22

Swordfish

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2 Comments

Miguel Lanto Over a year ago

13 9 C:\Users\Migs\Desktop\Test-Codes\testing2.cpp [Error] 'is' was not declared in this scope This was my error trying the code!

Swordfish Over a year ago

That was a sample in which from context should be clear that is is a std::ifstream. Call it what you want.

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