I would like to know once and for all how to convert a double to a const char*

I've tried it a few times, but have never succeeded, I know it can be done, but I haven't figured out how to yet. I've tried some different things. Sometimes it won't compile, and sometimes the program crashes, and other times it ends up as an empty string.

9 Years
Discussion Span
Last Post by Seta00

depends on how you want to use it. If you want to pass a pointer to a double as a parameter to some function that takes char* then typecasting might work, depending on what that function is going to do with it. Normally, however, you will have to convert it storing the results in either a character array or a std::string object.

Two ways come to mind: sprintf() will convert and store in a character array, while std::stringstream will convert and store in std::string object.


>I would like to know once and for all how to convert a double to a const char*
Casting doesn't work. You're not converting the double to a string with a cast, you're telling the compiler to use the binary representation of the double as characters in a string. For a value like 12.35, that's not going to give you a string like "12.35". You need to take the printed value (like if you write the double using cout) and store it in a string. That's really really painful to do manually with floating-point, so you should use sprintf or stringstream like Ancient Dragon said.

This topic has been dead for over six months. Start a new discussion instead.
Have something to contribute to this discussion? Please be thoughtful, detailed and courteous, and be sure to adhere to our posting rules.