How to Safely Convert Strings to Double Precision Numbers in C ?

Converting Strings to Double Precision Numbers in C

When working with strings and numerical data in C , it's often necessary to convert strings to double precision floating-point numbers. This article explores a solution to this problem, with a focus on handling non-numerical strings gracefully.

The Function

To achieve the conversion, we define a function string_to_double that takes a string reference as input and returns a double value. Within this function:

• An std::istringstream object is initialized with the input string.
• A double variable x is declared to receive the result.
• The istringstream >> operator is used to extract data from the stream into the x variable.
• If the extraction fails due to non-numerical characters, the function returns 0.0.
• Otherwise, the extracted double value is returned.

Usage and Testing

In the provided example code, string_to_double is invoked with various string inputs to demonstrate its functionality:

• Simple cases return the expected double values.
• Leading or trailing whitespace is handled correctly.
• Non-digit characters after numbers are ignored.
• The function's limitation is its inability to distinguish between all valid string representations of zero (e.g., "0", "0.0", "0.0e0") and non-numerical strings.

Conclusion

The string_to_double function provides a simple and efficient way to convert strings to double precision floating-point numbers in C . Its handling of non-numerical strings ensures that it returns 0.0 in these cases, as per the requirement.

The above is the detailed content of How to Safely Convert Strings to Double Precision Numbers in C ?. For more information, please follow other related articles on the PHP Chinese website!