Check if a string can be converted to a double in C++

This tutorial will discuss about a unique way to check if a string can be converted to a double in C++.

To check if a string contains a valid double value or not, we can try to convert the string into a double using stod() function. If the conversion is successful, then we can confirm that string can be converted into a double. Whereas, if string contains any invalid_argument or some out_of_range value then it will throw an exception. In case we encounter an exception while converting a string to double using the stod() function, then we can confirm that string cannot be converted into a double.

Let’s see the complete example,

#include <iostream>
#include <string>

using namespace std;

// Check if string can be converted to a Double
bool isDouble(const string& str)
{
    bool result = true;
    try
    {
        // Convert string to double
        double d = stod(str);
    }
    catch (const invalid_argument& e)
    {
        // handle the exceptiop invalid_argument
        result = false;
    }
    catch (const out_of_range& e)
    {
        // handle the exceptiop out_of_range
        result = false;
    }
    return result;
}

int main()
{
    string strValue = "8.907";

    // Check if string can be converted into a double
    if (isDouble(strValue))
    {
        cout << "Yes, string can be converted to a double" << endl;
    }
    else
    {
        cout << "No, string can not be converted to a double" << endl;
    }

    return 0;
}

Output :

Yes, string can be converted to a double

Summary

Today we learned about several ways to check if a string can be converted to a double in C++. Thanks.