How Would I Read From An External File [duplicate] - c++

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Getting input from external files?
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Closed 9 years ago.
Basically, I need a basic .txt -- maybe a .csv -- file that is going to be read by the program and use a number located in the file.
I would want the file to look like this:
oranges: 1.50
apples: 2.10
pears: 4.70
I would then want the program to read 1.50 from the first line and assign that to the variable orangeCost. I would then want the second part to read the second line and assign 2.10 to the variable apples, etc.
This is what I have so far:
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main() {
int garden();
//Lawn
int lawnLength;
int lawnWidth;
int lawnTime = 20;
float lawnCost = 15.50;
cout << "Length of lawn required: "; // Asks for the length
cin >> lawnLength; // Writes to variable
cout << "Width of lawn required: "; // Asks for the width
cin >> lawnWidth; // Writes to variable
int lawnArea = (lawnLength * lawnWidth); //Calculates the total area
cout << endl << "Area of lawn required is " << lawnArea << " square meters"; //Prints the total area
cout << endl << "This will cost a total of " << (lawnArea * lawnCost) << " pounds"; //Prints the total cost
cout << endl << "This will take a total of " << (lawnArea * lawnTime) << " minutes" << endl << endl; //Prints total time
//Concrete Patio
int concreteLength;
int concreteWidth;
int concreteTime = 20;
float concreteCost = 20.99;
cout << "Length of concrete required: "; // Asks for the length
cin >> concreteLength; // Writes to variable
cout << "Width of concrete required: "; // Asks for the width
cin >> concreteWidth; // Writes to variable
int concreteArea = (concreteLength * concreteWidth); //Calculates the total area
cout << endl << "Area of concrete required is " << concreteArea << " square meters"; //Prints the total area
cout << endl << "This will cost a total of " << (concreteArea * concreteCost) << " pounds"; //Prints the total cost
cout << endl << "This will take a total of " << (concreteArea * concreteTime) << " minutes" << endl << endl; //Prints total time
//Wooden Deck
int woodenDeckLength;
int woodenDeckWidth;
int woodenDeckTime = 30;
float woodenDeckCost = 15.75;
cout << "Length of wooden deck required: "; // Asks for the length
cin >> woodenDeckLength; // Writes to variable
cout << "Width of wooden deck required: "; // Asks for the width
cin >> woodenDeckWidth; // Writes to variable
int woodenDeckArea = (woodenDeckLength * woodenDeckWidth); //Calculates the total area
cout << endl << "Area of wooden deck required is " << woodenDeckArea << " square meters"; //Prints the total area
cout << endl << "This will cost a total of " << (woodenDeckArea * woodenDeckCost) << " pounds"; //Prints the total cost
cout << endl << "This will take a total of " << (woodenDeckArea * woodenDeckTime) << " minutes" << endl << endl; //Prints total time
//Rectangular Pond
int rectangularPondLength;
int rectangularPondWidth;
int rectangularPondTime = 45;
float rectangularPondCost = 25.00;
cout << "Length of rectangular pond required: "; // Asks for the length
cin >> rectangularPondLength; // Writes to variable
cout << "Width of rectangular pond required: "; // Asks for the width
cin >> rectangularPondWidth; // Writes to variable
int rectangularPondArea = (rectangularPondLength * rectangularPondWidth); //Calculates the total area
cout << endl << "Area of rectangular pond required is " << rectangularPondArea << " square meters"; //Prints the total area
cout << endl << "This will cost a total of " << (rectangularPondArea * rectangularPondCost) << " pounds"; //Prints the total cost
cout << endl << "This will take a total of " << (rectangularPondArea * rectangularPondTime) << " minutes" << endl << endl; //Prints total time
//Water Features
int waterFeatures;
int waterFeaturesTime = 60;
float waterFeaturesCost = 150.00;
cout << "Number of water features required: "; // Asks for the amount of water features needed
cin >> waterFeatures; // Writes to variable
cout << endl << "Number of water feature(s) required is " << waterFeatures << " water feature(s)"; //Prints the total area
cout << endl << "This will cost a total of " << (waterFeatures * waterFeaturesCost) << " pounds"; //Prints the total cost
cout << endl << "This will take a total of " << (waterFeatures * waterFeaturesTime) << " minutes" << endl << endl; //Prints total time
//Garden Lights
int gardenLights;
int gardenLightsTime = 10;
float gardenLightsCosts = 5.00;
cout << "Number of garden lights required: "; // Asks for the amount of water features needed
cin >> gardenLights; // Writes to variable
cout << endl << "Number of garden light(s) required is " << gardenLights << " garden light(s)"; //Prints the total area
cout << endl << "This will cost a total of " << (gardenLights * gardenLightsCosts) << " pounds"; //Prints the total cost
cout << endl << "This will take a total of " << (gardenLights* gardenLightsTime) << " minutes" << endl << endl; //Prints total time
//Quotation
string quotation;
cout << "Do you want to save a quotation? " << endl; //Asks if they want to save a quotation
cin >> quotation; //Saves if they want to save a quotation or not
if (quotation == "yes")
{
std::string nameOfFile;
cout << "What would you like to save the quotation as? (Maybe using your last name) " << endl;
cin >> nameOfFile;
ofstream outfile(nameOfFile + ".txt"); // Opens file in write mode
//Lawn
outfile << "The total lawn area is " << lawnArea << " square meters" << endl; // Writes users data into the file
outfile << "The total cost for the lawn is £" << (lawnArea * lawnCost) << endl; // Writes users data into the file
outfile << "The total time for the lawn is " << (lawnArea * lawnTime) << " minutes" << endl << endl; // Writes users data into the file
//Concrete Patio
outfile << "The total concrete patio area is " << concreteArea << " square meters" << endl;
outfile << "The total cost for the concrete patio is £" << (concreteArea * concreteCost) << endl;
outfile << "The total time for the concrete patio is " << (concreteArea * concreteTime) << " minutes" << endl << endl;
//Wooden Deck
outfile << "The total wooden deck area is " << woodenDeckArea << " square meters" << endl;
outfile << "The total cost for the wooden deck is £" << (woodenDeckArea * woodenDeckCost) << endl;
outfile << "The total time for the wooden deck is " << (woodenDeckArea * woodenDeckTime) << " minutes" << endl << endl;
//Rectangular Pond
outfile << "The total rectangular pond area is " << rectangularPondArea << " square meters" << endl;
outfile << "The total cost for the wooden deck is £" << (rectangularPondArea * rectangularPondCost) << endl;
outfile << "The total time for the wooden deck is " << (rectangularPondArea * rectangularPondTime) << " minutes" << endl << endl;
//Water Features
outfile << "The total number of water feature(s) needed are " << waterFeatures << endl;
outfile << "The total cost for the water feature(s) is £" << (waterFeatures * waterFeaturesCost) << endl;
outfile << "The total time for the water feature(s) is " << (waterFeatures * waterFeaturesTime) << " minutes" << endl << endl;
//Garden Lights
outfile << "The total number of garden light(s) needed are " << gardenLights << endl;
outfile << "The total cost for the garden light(s) is £" << (gardenLights * gardenLightsCosts) << endl;
outfile << "The total time for the garden light(s) is " << (waterFeatures * waterFeaturesTime) << " minutes" << endl << endl;
//CLOSE FILE
outfile.close(); // Close's the file.
cout << "Quotation saved." << endl;
}
else
{
cout << "Quotation not saved." << endl;
}
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
cin.ignore( numeric_limits<streamsize>::max(), '\n' );
return 0;
}
Thank you for any help! :)

Answer 1

Here's a way of doing it:
Create a class fruit with private variables name and cost.
Then create a constructor that takes a string (a line from the input file). Extract everything up to ':' into name and the value that follows into cost.
Your function that read file needs to do something like this:
declare an array of fruit
loop:
get a line from file into a variable
call the fruit class with this variable, and add the created object into an array
When you reach the end of the file, you have an array of fruits that contains all the data from the file.
to learn about classes, check: http://www.tutorialspoint.com/cplusplus/cpp_classes_objects.htm
to learn about reading from files, check: http://www.cplusplus.com/doc/tutorial/files/