Programming Forums > Application Development > C

bivhitscar · Oct 30th, 2005, 1:52 AM

Here's the code:

int main(void)
{
  double value;           

  printf("Enter a temperature in Farenheit: ");
  scanf("%f", &value);
  printf("%f", value);
  
  return 0;
}

Obviously this is part of a bigger program, but this really should work, although I can't figure out why it doesn't. I've tried entering numbers with decimal values, but the result is always 0.000000.

It does seem to work if I change 'value' to float instead of double, but I don't want that.

Any suggestions?

I'm using the VC++ free tools from M$ if that makes a difference.

andro · Oct 30th, 2005, 2:12 AM

Try using %lf instead of %f

bivhitscar · Oct 30th, 2005, 2:17 AM

It works. Hmm, why is it that the book I'm using makes no mention of the %lf property? It is from like 2001, but I didn't think it would be too outdated.

Thanks.

Narue · Oct 30th, 2005, 8:50 AM

>why is it that the book I'm using makes no mention of the %lf property?
Probably because it doesn't cover scanf adequately. That suggests your book isn't of the reference category, but more of a tutorial that's cut down to be easier to follow. Books like that typically use float instead of double for some strange reason, and %f means "pointer to float" to scanf. On the other hand, if your book actually does use %f with double, you should probably toss the book and get a better one. If an author makes such ameteurish mistakes, it's unlikely that he can properly teach you C.

Oct 30th, 2005, 1:52 AM	#1
bivhitscar Hobbyist Programmer Join Date: Oct 2005 Location: Melbourne, Australia Posts: 126 Rep Power: 4	Retreiving a double from scanf() using "%f" Here's the code: (Toggle Plain Text) int main(void) { double value; printf("Enter a temperature in Farenheit: "); scanf("%f", &value); printf("%f", value); return 0; } int main(void) { double value; printf("Enter a temperature in Farenheit: "); scanf("%f", &value); printf("%f", value); return 0; } Obviously this is part of a bigger program, but this really should work, although I can't figure out why it doesn't. I've tried entering numbers with decimal values, but the result is always 0.000000. It does seem to work if I change 'value' to float instead of double, but I don't want that. Any suggestions? I'm using the VC++ free tools from M$ if that makes a difference.

Oct 30th, 2005, 2:17 AM	#3
bivhitscar Hobbyist Programmer Join Date: Oct 2005 Location: Melbourne, Australia Posts: 126 Rep Power: 4	It works. Hmm, why is it that the book I'm using makes no mention of the %lf property? It is from like 2001, but I didn't think it would be too outdated. Thanks. __________________ it's ironic considerate rarity patron of love higher knowledge engulfs me...

Oct 30th, 2005, 8:50 AM	#4
Narue Professional Programmer Join Date: Sep 2005 Posts: 419 Rep Power: 4	>why is it that the book I'm using makes no mention of the %lf property? Probably because it doesn't cover scanf adequately. That suggests your book isn't of the reference category, but more of a tutorial that's cut down to be easier to follow. Books like that typically use float instead of double for some strange reason, and %f means "pointer to float" to scanf. On the other hand, if your book actually does use %f with double, you should probably toss the book and get a better one. If an author makes such ameteurish mistakes, it's unlikely that he can properly teach you C. __________________ Even if the voices aren't real, they have some pretty good ideas.

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Oct 30th, 2005, 2:12 AM	#2
andro Professional Programmer Join Date: Oct 2005 Location: California Posts: 319 Rep Power: 4	Try using %lf instead of %f

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Programming Forums > Application Development > C

Retreiving a double from scanf() using "%f"