Reading Floats from a txt file in C++ - c++

Question

I am trying to read (x,y) floating point values from a txt file in C++. The numbers are separated by a space. The ith number and the i+1th number make the (x,y) coordinates. So index positions 0 and 1 would be the first (x,y) pair and index positions (1,2) would be the next (x,y) pair.
This is what I have done but I am not sure how I can save them as floats.
ifstream randomFile;
string content;
randomFile.open("random.txt");
if(randomFile.is_open()) {
while(getline(randomFile,content)){
randomFile >> content;
}
randomFile.close();
}

Answer 1

Read the first float x
While additional read y succeeds:
  Add (x, y) to your list
  x = y
#include <iostream>
#include <vector>
struct xy
{
float x, y;
xy( float x, float y ) : x{x}, y{y} { }
};
auto read_xy_pairs( std::istream & ins )
{
std::vector<xy> xys;
float x, y;
ins >> x;
while (ins >> y)
{
xys.emplace_back( x, y );
x = y;
}
return xys;
}
#include <sstream>
#include <string>
int main()
{
std::cout << "list of numbers? ";
std::string s;
getline( std::cin, s );
std::istringstream numbers( s );
for (auto [x, y] : read_xy_pairs( numbers ))
std::cout << "(" << x << ", " << y << ")\n";
}
Example:
list of numbers? 1 2 3 4 5
(1, 2)
(2, 3)
(3, 4)
(4, 5)

Answer 2

An extra variable (prev) can be used to store the value of last input and append (prev,curr) on every iteration to the storage container. In the following code, I have used vector of pairs of float to store the pairs, but you may use arrays or structures as well.
#include<fstream>
#include<iostream>
#include<vector>
using namespace std;
int main() {
//Declaring vector of float pairs
vector <pair<float, float>> floatPairs;
ifstream randomFile;
float curr, prev;
randomFile.open("a.txt");
randomFile >> curr;
while (!randomFile.eof()) {
prev = curr;
randomFile >> curr;
//Appending to vector of float pairs
floatPairs.push_back({ prev,curr });
}
//Printing
for (auto i : floatPairs) {
cout << "(" << i.first << ", " << i.second << ")\n";
}
}
Input file content: 12.5 56.8 34.7 75.7 23.4 86.7 34.9 66.8
Output:
(12.5, 56.8)
(56.8, 34.7)
(34.7, 75.7)
(75.7, 23.4)
(23.4, 86.7)
(86.7, 34.9)
(34.9, 66.8)