Using ifstream::operator>> to load an array from a CSV file

Question

I know there are several C++ ways to load in values from a CSV, but I'm curious, how can I adapt this incorrect approach with the minimal changes necessary to make it work:

std::ifstream fileStream ("File.txt");    // File.txt reads "1,2,3"
short numbers[3];

for (short i = 0; i < 3; ++i)
    fileStream >> numbers[i];

Is there any way that I can do this using ifstream::operator>>, while keeping as conceptually close as possible to this implementation? Fix this code! :-)

Thanks! Believe it or not, this will be very helpful in a computational neutrino physics project I'm working on.

Dima Chubarov · Accepted Answer · 2012-09-29 06:39:36Z

3

As a quick fix reading the comma into a temporary variable will let you get the data out of the file.

std::ifstream fileStream ("File.txt"); 
short numbers[3];
char delim;

fileStream >> numbers[0];
for (int i = 1; i < 3; ++i){
    fileStream >> delim;
    fileStream >> numbers[i];
}

answered Sep 29, 2012 at 6:39

Dima Chubarov

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1 Comment

UltraBird Over a year ago

Hooray! I was assuming operator>> would just keep skipping along until it reached the next variable of the type being loaded, but it was getting hung up on the commas, as you said.

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