C++ String to float/double and vice-versa

C++ string to float and double Conversion

The easiest way to convert a string to a floating-point number is by using these C++11 functions:

• std::stof() - convert string to float
• std::stod() - convert string to double
• std::stold() - convert string to long double.

These functions are defined in the string header file.

Example 1: C++ string to float and double

Output

num_float = 123.457
num_double = 123.457

Example 2: C++ char Array to double

We can convert a char array to double by using the std::atof() function.

Output

num_double = 123.457

C++ float and double to string Conversion

We can convert float and double to string using the C++11 std::to_string() function. For the older C++ compilers, we can use std::stringstream objects.

Example 3: float and double to string Using to_string()

Output

Float to String = 123.456703
Double to String = 123.456700

Example 4: float and double to string Using stringstream

Output

Float to String = 123.457
Double to String = 123.457

Recommended Reading: C++ string to int.