Discussion in "Software" started by    bhagirath    Jul 5, 2011.
Tue Jul 05 2011, 04:19 AM
#1
Hi all,

I am a newbie to Keil. I was just working in one demo project and stuck in between due to some access violation error. I tried googleing to various forums but didn't work, also tried applying map command but no success may be anyone could provide proper steps to do so. So could can one please help me in this regards? My code is as follows

//start
#include<reg51.h>

#include<string.h>


char var1[1];
char var2[1];
char var3[1];
char var4[5];
char var5[5];
char var6[1];
char var7[1];

void main()
{
    while(1)
    {
        char str[]= "123456789123456";
        int idx1 = 0;
        int index2 = 1;
        strncpy (var1,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var2,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);
        idx1+=5;
        index2+=5;
        strncpy (var4,str+idx1,index2);
        idx1+=1;
        index2+=5;
        strncpy (var5,str+idx1,index2);
        idx1+=5;
        index2+=1;
        strncpy (var6,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var7,str+idx1,index2);
    }
}
//end


The error comes while debugging the code, here any where in between it stops debugging and throws error 65 access violation error.
If possible please reply me with steps to resolve this. Let me know if you want further information.

Thanks in advance

Info: Keil version 3.0 eval, hardware : AT89S52
Tue Jul 05 2011, 06:22 PM
#2
For a start,to find an error remove all the code you can until the error disappears.
In this case everything in your while loop.
Then put back a bit at a time until the error comes back .
This tells you where to look.

Your error(s) come from the use of strncpy.
Most of your target buffers are only one byte long and yet you are often trying to copy
more than one byte into them.
This means you are "violating" memory space you "don't own"



[ Edited Wed Jul 06 2011, 03:28 PM ]
Wed Jul 06 2011, 07:52 AM
#3
Hi ExperimenterUK,

Thank you very much for reply,

As per your advice I have removed all the multiple characters trimming, now I am doing only on single character, but then also I am getting the same error. I had googled on this error and some where it was mentioned to keep the code in single loop thats why i have kept it under while(1).

#include<reg51.h>

#include<string.h>


char var1[1];
char var2[1];
char var3[1];
char var4[1];
char var5[1];
char var6[1];
char var7[1];

void main()
{
    while(1)
    {
        char str[]= "123456789123456";
        unsigned char idx1 = 0;
        unsigned char index2 = 1;
        strncpy (var1,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var2,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);
		idx1+=1;
        index2+=1;
        strncpy (var4,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var5,str+idx1,index2);// here the location of error..
        idx1+=1;
        index2+=1;
        strncpy (var6,str+idx1,index2);
        idx1+=1;
        index2+=1;
       	strncpy (var7,str+idx1,index2);
		break;
    }
}


I will be really grateful to you if you could try this in your environment.

According to my requirement I need to perform substring function on one string, thats why i have kept strncpy().

Thanks once again.
Wed Jul 06 2011, 08:31 AM
#4
I tried your code on My keil, it didnt showed any error,
Check your keil with other programs(simple one)
Wed Jul 06 2011, 09:16 AM
#5
Hi kirangowle,

I am getting error on debugging the code line by line. The code compiles fine with keil. the only issue
is while debugging it throws error for access violation.

Could you please try debugging the code?

Thanks
Bhagirath
Wed Jul 06 2011, 10:22 AM
#6
Hi,
I debugged your code, it was getting halt at strncpy(var3,)

In array declaration i increased the array length to 5(var[5]) and keep the local variable declaration outside of the while(1).
Wed Jul 06 2011, 11:31 AM
#7
Hi Kirangowle,

Thanks for reply,

I have changed the code as you have suggested, for performance and testing issue i have changed the capacity for each var to 1 byte. But no success, in debugging it stops at var5, after which i have noticed that all variables are cleared which were holding their values before error. here is my changed code

char var1[1];
char var2[1];
///...
char var7[1];
char str[]= "123456789123456";
char idx1 = 0;
char index2 = 1;

void main()
{

    while(1)
    {
        strncpy (var1,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var2,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);
		idx1+=1;
        index2+=1;
        strncpy (var4,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var5,str+idx1,index2);
        idx1+=1;
        index2+=1;
        strncpy (var6,str+idx1,index2);
        idx1+=1;
        index2+=1;
       	strncpy (var7,str+idx1,index2);
		
    }
}


Wed Jul 06 2011, 12:26 PM
#8
You didnt change the array length from var[1] to var[5].
i am not understanding what basically u are try to achieve .
Wed Jul 06 2011, 01:34 PM
#9
Hi,

Let me describe my workflow here, I want to substring the "str" in different segments. Let say that segments would be like
var1 = first character
var2 = 2nd - 4th
var3 = 5th - 8th
like wise, it is my custom requirement.

In given example i have created var1[1] - var7[1] just to check, because it was some times showing error in array with bigger ranges. Actually it will be as describe above.e.g.
var1[1], var2[3], var2[4], var4[1]....

Hope this clears it..

And in doing so keil is throwing the error of either access violation or it stops debugging.
Wed Jul 06 2011, 03:51 PM
#10


Hi ExperimenterUK,
As per your advice I have removed all the multiple characters trimming, now I am doing only on single character,

bhagirath


Actually I meant remove all the statements,then put back one statement at a time.


I had googled on this error and some where it was mentioned to keep the code in single
loop thats why i have kept it under while(1).

bhagirath


Whatever you Googled is not relevent here,remove the while() loop, or at least move it to the end

Remove this line for now " index2+=1; " it makes you copy more bytes each time


Try this
#include<reg51.h>
#include<string.h>
char var1[1];
char var2[1];
char var3[1];

void main()
{

    
        char str[]= "123456789123456";
        unsigned char idx1 = 0;
        unsigned char index2 = 1;
        strncpy (var1,str+idx1,index2);  //this should work
        idx1+=1;
 //;  index2+=1; don't do this as it copies 2 bytes next time

        strncpy (var2,str+idx1,index2);   //this should work
        idx1+=1;
        index2+=1;
        strncpy (var3,str+idx1,index2);   //this should not  work
//;		break;  // ??? not needed
    while(1);

}


Get Social

Information

Powered by e107 Forum System

Conversation

Sat Aug 01 2015, 05:57 AM
ghulamqadir
i want to communitcate wifi module with android phone using pic18f4550. Any Suggestion????????
Sat Aug 01 2015, 05:56 AM
ghulamqadir
Slam
ExperimenterUK
Thu Jul 30 2015, 11:41 PM
@Muhammad Aarshad build what ?
Wed Jul 29 2015, 06:42 PM
Muhammad Aarshad
Hello I want to build it, but I don't know how can I program the micro controller. Can You send me the code of the IC? Thanks in advance My e-mail: [email protected]
Sat Jul 25 2015, 10:37 PM
Arnali
What does the cross means? The ones from pin 7,8,9,10 of the LCD?
Fri Jul 24 2015, 09:53 AM
HARSHAL PATIL
....
shyam
Thu Jul 23 2015, 01:42 PM
hi Ajay
ajay_bhargav
Mon Jul 20 2015, 04:38 AM
@Rohit Biradar, I am glad my tutorial helped
Thu Jul 16 2015, 06:19 PM
Rohit Biradar
Thanks a lot publisher of this tutorial. Everybody tells about the nibble sending methods and the command set for 4-wire lcd interface. You are the first to tell me about the most important part that is resetting the lcd. This thing got me all day. Now I can sleep in peace. Thanks once again. Million thanks.
Thu Jul 16 2015, 12:24 PM
Baby
my project is related to control the door in dam. by keil program how can i control the same.

Downloads

Comments

albatain
Fri Jul 31 2015, 02:58 AM
KDN
Wed Jul 29 2015, 05:14 AM
Tanvir.
Fri Jul 24 2015, 07:59 AM
erummumtaz
Thu Jul 23 2015, 10:47 PM
balvant
Thu Jul 16 2015, 03:56 PM
seoulmak
Mon Jul 13 2015, 01:21 PM
SHIVKHUMAR
Sat Jul 11 2015, 04:10 AM
Nals99
Fri Jul 03 2015, 08:33 AM

Online

Guests: 37, Members: 0 ...

most ever online: 182184
(Members: , Guests: 182184) on 06 Aug 2010: 05:37 AM

Members: 37679
Newest member: albatain
Forum Activity
Mc_Comet32 Avatar
Posted By Mc_Comet32
Sun Jul 26 2015, 05:49 PM
ExperimenterUK Avatar
Posted By ExperimenterUK
Thu Jul 23 2015, 08:14 PM
Try this link.Basically find the tacho output pin...
seoulmak Avatar
Posted By seoulmak
Mon Jul 20 2015, 03:44 PM
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 20 2015, 04:42 AM
Ok then, check if you did not mention "LCD_ClearSc...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 20 2015, 04:41 AM
I am assuming you're talking about the small CPU f...
ajay_bhargav Avatar
Posted By ajay_bhargav
Mon Jul 20 2015, 04:36 AM
Amit Kumar Das Avatar
Posted By Amit Kumar Das
Sun Jul 19 2015, 04:17 AM
Yes they are fine. I have included everything. Una...
seoulmak Avatar
Posted By seoulmak
Fri Jul 17 2015, 08:41 AM
yes, but i need more information to connect the f...
balvant Avatar
Posted By balvant
Thu Jul 16 2015, 04:07 PM
ExperimenterUK Avatar
Posted By ExperimenterUK
Wed Jul 15 2015, 05:42 PM
Is this a project listed on this site ?