UPDATE: I am passing a string variable and am iterating through the string character by character. Whenever I run into a decimal, I want to combine the previous position on the string (ie 2) and the next position in the string (ie 5) into a double. So how would I go about making the char 2, char . , char 5 into one whole double value (2.5)? Without using STL classes or Vectors. What I went ahead and tried was the following below. However, whenever I do the stuff in the var line, it doesn't hold the value 2.5 as a string. It holds a: "•". Is there something wrong that I am doing?
If your point is to parse strings to doubles, I would take a different approach to iterate through the string. First, I would create an iterator splited by space to avoid checking if there is a '.'. And then I would iterate through this new iterator. Something like this
#include <iostream>
#include <string>
#include <sstream>
#include <iterator>
#include <vector>
int main() {
using namespace std;
double num;
string variableName = "4 5 7 2.5";
istringstream iss(variableName);
vector<string> nums{istream_iterator<string>{iss},
istream_iterator<string>{}};
for (int i = 0; i < nums.size(); i++) {
num = stod(nums[i]);
}
return 0;
}
The advantage of this approach is that it works regardless on how many characters are before and after the decimal point.
I would do something like this:
double x;
std::string temp = "";
std::string variableName = "4 5 7 2.5";
std::string::size_type sz; // alias of size_t
for (int i = 0; i < variableName.length(); i++) // iterates through variableName
{
if (variableName[i] == '.') {
temp += variableName[i - 1];
temp += variableName[i];
temp += variableName[i + 1];
x = stod(temp, &sz);
}
}
return x;
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