• Binarydepth (14/14) Jul 09 2015 This is my code :
• Adam D. Ruppe (7/8) Jul 09 2015 You didn't initialize this variable. Set it to 0.0 and it will
• Binarydepth (2/10) Jul 09 2015 Thank you very much!! :D
• bachmeier (7/15) Jul 09 2015 Is there a reason the compiler doesn't identify this as an error?
• Adam D. Ruppe (4/6) Jul 09 2015 The compiler just doesn't really try to trace if variables have
• Steven Schveighoffer (5/17) Jul 09 2015 prom has been initialized, to NaN by the compiler. It's not an accident.
• flamencofantasy (2/16) Jul 11 2015 foreach(nem; 0..3)
• Steven Schveighoffer (8/24) Jul 13 2015 that is a good catch, if the purpose is to fill in all 3 nums elements.
• Binarydepth (3/30) Apr 10 2017 You mean with readf ?
• Binarydepth (2/19) Apr 10 2017 Yes, Thank you!!

"Binarydepth" <binarydepth gmail.com> writes:

This is my code :
import std.stdio : writeln, readf;
void main()	{
	int[3] nums;
	float prom;
	foreach(nem; 0..2)	{
		writeln("input a number : ");
		readf(" %d", &nums[nem]);
		prom+=nums[nem];
	}
	writeln(prom/3.0);
}

I get prompted two times for a number and I then get NAN out of 
nowhere.

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
 	float prom;

You didn't initialize this variable. Set it to 0.0 and it will 
work.

Like how pointers are initialized to null automatically in D, 
floats are auto initalized to NaN in D. The idea is to make use 
of an uninitialized variable obvious quickly so you are 
encouraged to initialize it.

"Binarydepth" <binarydepth gmail.com> writes:

On Thursday, 9 July 2015 at 15:18:18 UTC, Adam D. Ruppe wrote:
 On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
 	float prom;

 You didn't initialize this variable. Set it to 0.0 and it will 
 work.

 Like how pointers are initialized to null automatically in D, 
 floats are auto initalized to NaN in D. The idea is to make use 
 of an uninitialized variable obvious quickly so you are 
 encouraged to initialize it.

Thank you very much!! :D

"bachmeier" <no spam.com> writes:

On Thursday, 9 July 2015 at 15:18:18 UTC, Adam D. Ruppe wrote:
 On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
 	float prom;

 You didn't initialize this variable. Set it to 0.0 and it will 
 work.

 Like how pointers are initialized to null automatically in D, 
 floats are auto initalized to NaN in D. The idea is to make use 
 of an uninitialized variable obvious quickly so you are 
 encouraged to initialize it.

Is there a reason the compiler doesn't identify this as an error? 
prom+=nums[nem]; doesn't make sense if prom hasn't been 
initialized. I'm not seeing how treating it as NaN is a solution. 
Since it's possible that an NaN value is legitimate, you'd either 
have to litter your code with assertions, or take a chance that 
something that a problem will show up at a later date.

"Adam D. Ruppe" <destructionator gmail.com> writes:

On Thursday, 9 July 2015 at 17:04:43 UTC, bachmeier wrote:
 Is there a reason the compiler doesn't identify this as an 
 error?

The compiler just doesn't really try to trace if variables have 
actually been initialized or not. It punts it to runtime for 
simplicity of compiler implementation.

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 7/9/15 1:04 PM, bachmeier wrote:
 On Thursday, 9 July 2015 at 15:18:18 UTC, Adam D. Ruppe wrote:
 On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
     float prom;

 You didn't initialize this variable. Set it to 0.0 and it will work.

 Like how pointers are initialized to null automatically in D, floats
 are auto initalized to NaN in D. The idea is to make use of an
 uninitialized variable obvious quickly so you are encouraged to
 initialize it.

 Is there a reason the compiler doesn't identify this as an error?
 prom+=nums[nem]; doesn't make sense if prom hasn't been initialized.

prom has been initialized, to NaN by the compiler. It's not an accident.

All data is default initialized in D unless specifically initialized to 
void.

-Steve

"flamencofantasy" <flamencofantasy gmail.com> writes:

On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
 This is my code :
 import std.stdio : writeln, readf;
 void main()	{
 	int[3] nums;
 	float prom;
 	foreach(nem; 0..2)	{
 		writeln("input a number : ");
 		readf(" %d", &nums[nem]);
 		prom+=nums[nem];
 	}
 	writeln(prom/3.0);
 }

 I get prompted two times for a number and I then get NAN out of 
 nowhere.

foreach(nem; 0..3)

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 7/11/15 12:57 PM, flamencofantasy wrote:
 On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
 This is my code :
 import std.stdio : writeln, readf;
 void main()    {
     int[3] nums;
     float prom;
     foreach(nem; 0..2)    {
         writeln("input a number : ");
         readf(" %d", &nums[nem]);
         prom+=nums[nem];
     }
     writeln(prom/3.0);
 }

 I get prompted two times for a number and I then get NAN out of nowhere.

 foreach(nem; 0..3)

that is a good catch, if the purpose is to fill in all 3 nums elements.

Note, a future-proof version would say:

foreach(nem; 0..nums.length)

A more d-idiomatic way is to say:

foreach(ref nem; nums)

And then use nem anywhere you see nums[nem]

-Steve

Binarydepth <binarydepth gmail.com> writes:

On Monday, 13 July 2015 at 14:29:57 UTC, Steven Schveighoffer 
wrote:
 On 7/11/15 12:57 PM, flamencofantasy wrote:
 On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
 This is my code :
 import std.stdio : writeln, readf;
 void main()    {
     int[3] nums;
     float prom;
     foreach(nem; 0..2)    {
         writeln("input a number : ");
         readf(" %d", &nums[nem]);
         prom+=nums[nem];
     }
     writeln(prom/3.0);
 }

 I get prompted two times for a number and I then get NAN out 
 of nowhere.

 foreach(nem; 0..3)

 that is a good catch, if the purpose is to fill in all 3 nums 
 elements.

 Note, a future-proof version would say:

 foreach(nem; 0..nums.length)

 A more d-idiomatic way is to say:

 foreach(ref nem; nums)

 And then use nem anywhere you see nums[nem]

 -Steve

You mean with readf ?

Binarydepth <binarydepth gmail.com> writes:

On Saturday, 11 July 2015 at 16:57:55 UTC, flamencofantasy wrote:
 On Thursday, 9 July 2015 at 15:14:43 UTC, Binarydepth wrote:
 This is my code :
 import std.stdio : writeln, readf;
 void main()	{
 	int[3] nums;
 	float prom;
 	foreach(nem; 0..2)	{
 		writeln("input a number : ");
 		readf(" %d", &nums[nem]);
 		prom+=nums[nem];
 	}
 	writeln(prom/3.0);
 }

 I get prompted two times for a number and I then get NAN out 
 of nowhere.

 foreach(nem; 0..3)

Yes, Thank you!!