Mastering C++ Conversions: A Comprehensive Guide

Unlocking the Power of String Conversions

When working with C++, converting between data types is an essential skill to master. In this article, we’ll explore the easiest ways to convert strings to floating-point numbers and vice versa, using the latest C++11 functions.

Effortless String to Float and Double Conversions

The C++11 standard library provides three convenient functions to convert strings to floating-point numbers:

• std::stof() for converting strings to floats
• std::stod() for converting strings to doubles
• std::stold() for converting strings to long doubles

These functions are defined in the string header file, making it easy to incorporate them into your projects.

Example 1: C++ String to Float and Double Output

Let’s see these functions in action:

“`cpp

include

include

int main() {
std::string strFloat = “3.14”;
std::string strDouble = “3.14159”;

float f = std::stof(strFloat);
double d = std::stod(strDouble);

std::cout << "Float: " << f << std::endl;
std::cout << "Double: " << d << std::endl;

return 0;

}
“`

Converting Char Arrays to Double

But what about char arrays? We can use the std::atof() function to convert them to doubles:

“`cpp

include

include

int main() {
char strDouble[] = “3.14159”;

double d = std::atof(strDouble);

std::cout << "Double: " << d << std::endl;

return 0;

}
“`

The Reverse Conversion: Float and Double to String

Now, let’s explore how to convert float and double values back to strings. The C++11 std::to_string() function makes it easy:

“`cpp

include

include

int main() {
float f = 3.14;
double d = 3.14159;

std::string strFloat = std::to_string(f);
std::string strDouble = std::to_string(d);

std::cout << "Float: " << strFloat << std::endl;
std::cout << "Double: " << strDouble << std::endl;

return 0;

}
“`

Older C++ Compilers? No Problem!

For older C++ compilers, we can use std::stringstream objects to achieve the same result:

“`cpp

include

include

int main() {
float f = 3.14;
double d = 3.14159;

std::stringstream ss;
ss << f;
std::string strFloat = ss.str();

ss.str(""); // clear the stringstream
ss << d;
std::string strDouble = ss.str();

std::cout << "Float: " << strFloat << std::endl;
std::cout << "Double: " << strDouble << std::endl;

return 0;

}
“`

With these techniques under your belt, you’ll be able to effortlessly convert between strings and floating-point numbers in your C++ projects.