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digitalmars.D.learn - Access Violation

reply Robert Jones <robertjones21 HotPOP.com> writes:
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Why am i getting an access violation:

C:\Documents and Settings\jareth\Desktop>dmd -v -w ly2au.d
parse     ly2au
semantic  ly2au
semantic2 ly2au
semantic3 ly2au
code      ly2au
generating code for function 'main'
c:\dmd\bin\..\..\dm\bin\link.exe ly2au,,,user32+kernel32/noi;

C:\Documents and Settings\jareth\Desktop>ly2au
Enter number of light years: 5
Error: Access Violation

Attached is the source code.
May 11 2006
next sibling parent "Chris Miller" <chris dprogramming.com> writes:
On Thu, 11 May 2006 13:35:05 -0400, Robert Jones  
<robertjones21 HotPOP.com> wrote:

 Why am i getting an access violation:

 C:\Documents and Settings\jareth\Desktop>dmd -v -w ly2au.d
 parse     ly2au
 semantic  ly2au
 semantic2 ly2au
 semantic3 ly2au
 code      ly2au
 generating code for function 'main'
 c:\dmd\bin\..\..\dm\bin\link.exe ly2au,,,user32+kernel32/noi;

 C:\Documents and Settings\jareth\Desktop>ly2au
 Enter number of light years: 5
 Error: Access Violation

 Attached is the source code.

Your scanf is wrong; it takes a pointer to a float, not a real; or you can use %lf for double*. double tempx; scanf("%lf", &tempx); x = tempx;
May 11 2006
prev sibling next sibling parent David Medlock <noone nowhere.com> writes:
Robert Jones wrote:
 Why am i getting an access violation:
 
 C:\Documents and Settings\jareth\Desktop>dmd -v -w ly2au.d
 parse     ly2au
 semantic  ly2au
 semantic2 ly2au
 semantic3 ly2au
 code      ly2au
 generating code for function 'main'
 c:\dmd\bin\..\..\dm\bin\link.exe ly2au,,,user32+kernel32/noi;
 
 C:\Documents and Settings\jareth\Desktop>ly2au
 Enter number of light years: 5
 Error: Access Violation
 
 Attached is the source code.
 
 
 ------------------------------------------------------------------------
 
 import std.c.stdio;
 import std.stdio;
 
  // number of kilometers in a astronomical unit 
 const real au = 148800000.0;
  // number of kilometers in a light year based on light second being exactly
300,000km
 const real ly = 9467280000000.0;
 real n;
 real x;
 real y;
 
 int main()
 in
 {
 	assert(au is 148800000.0); // ensure that au is exactly 1,448,800,000km
 	assert(ly is 9467280000000.0); // ensure that ly is exactly
9,467,280,000,000km
 }
 body
 {
 	writef("Enter number of light years: ");
 	scanf("%f", x);
 	
 	// convert light years to kilometers
 	y = x * ly;
 	
 	 // convert kilometers to astonomical units
 	n = y / au;
 	
 	writefln("\nThe number of astronomical units is %f", n );
 	return 0;
 }

2 Problems I can see: 1) scanf requires the address of a float, so use &x 2) initialize those reals to some value, or you will get nan -DavidM
May 11 2006
prev sibling parent Robert Jones <robertjones21 HotPOP.com> writes:
Robert Jones said the following on 5/11/2006 1:35 PM:
Thanks Chris and David, below are the changes to the source which now 
compiles and does what it is supposed to do.

 
 import std.c.stdio;
 import std.stdio;
 
  // number of kilometers in a astronomical unit 
 const real au = 148800000.0;

  // number of kilometers in a light year based on light second being exactly
300,000km
 const real ly = 9467280000000.0;

 real n;

 real x;

 real y;

 
 int main()
 in
 {
 	assert(au is 148800000.0); // ensure that au is exactly 1,448,800,000km
 	assert(ly is 9467280000000.0); // ensure that ly is exactly
9,467,280,000,000km
 }
 body
 {
 	writef("Enter number of light years: ");
 	scanf("%f", x);

 	
 	// convert light years to kilometers
 	y = x * ly;
 	
 	 // convert kilometers to astonomical units
 	n = y / au;
 	
 	writefln("\nThe number of astronomical units is %f", n );
 	return 0;
 }

May 11 2006