c++ Receiving "-1.#IND" from output?

Question

Pretty simple problem here: When I test the wrong data input I give an error message but -1.#IND comes up after it?

for instance I type a negative where there should be a positive and I get "wrong input dummy-1.#IND"

#include "Header.h"

void error_rep(){
cout<<"Wrong input dummy";
}

double ctok(double c){
double j = c *273.15;
if (j >= -273.15){
return j;
}
else 
    error_rep();
}

int main(){
double c = 0;
cin >> c;

    double k = ctok(c);
    cout<<k<<endl;


keep_window_open();
}

What does this mean? and why is it coming up? How do I get rid of it?

for j < 273.15, your return value is not explicitly set, which means you can get an unexpected return value. — thang, Oct 09 '13 at 16:22
ctok returns double, but your else path does not return any double — taocp, Oct 09 '13 at 16:23
possible duplicate of [What do 1.#INF00, -1.#IND00 and -1.#IND mean?](http://stackoverflow.com/questions/347920/what-do-1-inf00-1-ind00-and-1-ind-mean) — GSerg, Oct 09 '13 at 16:27
Look at your code, think about it carefully. What did you want to happen in the error case? How does that match up to the code you actually wrote? — john, Oct 09 '13 at 16:27
possible duplicate of [Why the return value of double is -1.#IND?](http://stackoverflow.com/q/7476177/11683) — GSerg, Oct 09 '13 at 16:28

Mike Seymour · Answer 1 · 2013-10-09T16:29:58.283

What does this mean?

It's Microsoftese for "not a number". It means that k is not a valid floating-point number.

and why is it coming up?

When your range test fails, you don't return a value. This gives undefined behaviour; in practice, it's likely to be equivalent to returning an uninitalised value, which is likely to be garbage. Your compiler should warn you about this, if you have suitable warnings enabled.

How do i get rid of it?

I'd report the error by throwing an exception; then nothing can attempt to use the invalid return value if the function fails. Alternatively, you could return a type with a testable "invalid" state, such as boost::optional<double> or std::pair<double, bool>, and test it before use.

By the way, if that's supposed to be converting degrees Celsius to Kelvin, then you want to add 273.15, not multiply by it; and compare with zero after the conversion (or with 273.15 before converting, if you prefer).

score 1 · Accepted Answer · answered Oct 09 '13 at 16:29

A good compiler with all warning turns on, will have say that an execution path doesn't have a return ...,

 double ctok(double c){
 double j = c *273.15;
 if (j >= -273.15){
    return j;
 }
else {
     error_rep();
      ///here
      throw ;//somthing
}

}

and try-catch exception around ctok call

score 0 · Answer 3 · answered Oct 09 '13 at 16:24

0

-1.#IND means that the double value is "negative indefinate NaN". Basically the value stored can't be represented as a number in a double.

See http://blogs.msdn.com/b/oldnewthing/archive/2013/02/21/10395734.aspx

answered Oct 09 '13 at 16:24

Len Holgate

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c++ Receiving "-1.#IND" from output?

3 Answers3