How Can I Rewrite Without Stod()

Question

How can I rewrite my readDetails function without using stod() or strtod() in C++? The compiler I will be using doesn't have c++11 enabled and I get

'stod' was not declared in this scope error

int readDetails(SmallRestaurant sr[])
{
//Declaration
ifstream inf;

//Open file
inf.open("pop_density.txt");

//Check condition
if (!inf)
{
    //Display
    cout << "Input file is not found!" << endl;

    //Pause
    system("pause");

    //Exit on failure
    exit(EXIT_FAILURE);
}

//Declarations and initializations
string fLine;
int counter = 0;
int loc = -1;

//Read
getline(inf, fLine);

//Loop
while (inf)
{
    //File read
    loc = fLine.find('|');
    sr[counter].nameInFile = fLine.substr(0, loc);
    fLine = fLine.substr(loc + 1);
    loc = fLine.find('|');
    sr[counter].areaInFile = stod(fLine.substr(0, loc));  //line using stod
    fLine = fLine.substr(loc + 1);
    loc = fLine.find('|');
    sr[counter].popInFile = stoi(fLine.substr(0, loc));
    fLine = fLine.substr(loc + 1);
    sr[counter].densityInFile = stod(fLine);   //line using stod
    counter++;
    getline(inf, fLine);
}

//Return
return counter;
}

Below is the text I am trying to read:

Census Tract 201, Autauga County, Alabama|9.84473419420788|1808|183.651479494869 Census Tract 202, Autauga County, Alabama|3.34583234555866|2355|703.860730836106 Census Tract 203, Autauga County, Alabama|5.35750339330735|3057|570.60159846447

Thomas Matthews · Accepted Answer · 2017-07-08T00:05:18.777

0

Use std::istringstream.

std::string number_as_text("123");
int value;
std::istringstream number_stream(number_as_text);
number_stream >> value;

Edit 2: For those pedantic people:
The example below reads a double. Very similar pattern to the above reading of an integer.

std::string number_as_text("3.14159");
double pi;
std::istringstream number_stream(number_as_text);
number_stream >> pi;

You could also use a variant of sprintf.

Edit 1: Another parsing method
You could try:

std::string tract;
std::string county;
std::string state;
double value1;
char separator;

//...
std::ifstream input("myfile.txt");
//...
std::getline(input, tract, ',');
std::getline(input, county, ',');
std::getline(input, state, '|');
input >> value1;
input >> separator;
//...
input.ignore(100000, '\n'); // Ignore any remaining characters on the line

The above doesn't require separate string to number conversion.

edited Jul 08 '17 at 00:05

answered Jul 07 '17 at 23:50

Thomas Matthews

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1

Come on, this is not even the conversion they ask about. Also, that's obviously some dupe. – Baum mit Augen Jul 07 '17 at 23:52
1

@BaummitAugen: They are asking about converting string to decimal (number), which is what `std::istringstream` does. – Thomas Matthews Jul 07 '17 at 23:57
@BaummitAugen: There are a plethora of posts about how to read in a file, but they are all slightly different. This one has '|' as separators as well as ','. – Thomas Matthews Jul 07 '17 at 23:58
1

They are asking how to replace `stod`, and you answer how to parse some string to `int`. I know FGitW is important for that repz, but at least read the question in the title first. :/ – Baum mit Augen Jul 07 '17 at 23:59
Read the question carefully, they are asking to rewrite their function without using `stod`, which is what my answer presents. They are not asking specifically about a 1:1 function replacement for `stod`. – Thomas Matthews Jul 08 '17 at 00:01
1

So instead of using `stod` to convert `"9.84473419420788"`, they are supposed to read it into an `int`? – Baum mit Augen Jul 08 '17 at 00:02
See my "Edit 2". – Thomas Matthews Jul 08 '17 at 00:05
Thank you for the help. I will try this :) – TMosley Jul 08 '17 at 00:05

How Can I Rewrite Without Stod()

1 Answers1