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Old 10-28-2013, 05:25 AM   #1
pankaj8332
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Registered: Oct 2013
Posts: 2

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compilation error: text+0x1e undefined refrence to a function


i tried to compile this program which does a conversion of a string of characters form ascii to binary .
i dont understand how to fix this last error .



#include<stdio.h>
#include<stdlib.h>
#include<string.h>
char* asciitobinary(char* a);
int main(int argc ,char* argv[])
{
char* b;
b= asciitobinary(argv[1]);
printf("\n%s\n",b);
return 0;

}

char* asiitobinary(char* a)
{
char* b;
int len,j=0,k=0,i;
len=strlen(a);
for(i=0;i<len;i++)
{
for(k=j+7,j=j+7;k>=j;k--)
{

if(a[i]>1)
{
b[k]=a[i]%2;
a[i]=(a[i]-b[k])/2;
}
else
b[k]=0;
}

}
b[k]='\0';
return b;
}



error is this :
/tmp/cc4P9tCC.o: In function `main':
assignment.c.text+0x1e): undefined reference to `asciitobinary'
collect2: error: ld returned 1 exit status
 
Old 10-28-2013, 05:28 AM   #2
pankaj8332
LQ Newbie
 
Registered: Oct 2013
Posts: 2

Original Poster
Rep: Reputation: Disabled
Quote:
Originally Posted by pankaj8332 View Post
i tried to compile this program which does a conversion of a string of characters form ascii to binary .
i dont understand how to fix this last error .



#include<stdio.h>
#include<stdlib.h>
#include<string.h>
char* asciitobinary(char* a);
int main(int argc ,char* argv[])
{
char* b;
b= asciitobinary(argv[1]);
printf("\n%s\n",b);
return 0;

}

char* asiitobinary(char* a)
{
char* b;
int len,j=0,k=0,i;
len=strlen(a);
for(i=0;i<len;i++)
{
for(k=j+7,j=j+7;k>=j;k--)
{

if(a[i]>1)
{
b[k]=a[i]%2;
a[i]=(a[i]-b[k])/2;
}
else
b[k]=0;
}

}
b[k]='\0';
return b;
}



error is this :
/tmp/cc4P9tCC.o: In function `main':
assignment.c.text+0x1e): undefined reference to `asciitobinary'
collect2: error: ld returned 1 exit status
actually it compiled there was spelling mistakke
but not working
it is saying
segmentation fault core dumped
 
Old 10-28-2013, 09:07 AM   #3
GianfrancoD
LQ Newbie
 
Registered: Oct 2013
Location: Milan (Italy)
Distribution: Fedora Client / Centos Server
Posts: 1

Rep: Reputation: Disabled
Which is the size of char* b in asciitobinary() ?

Last edited by GianfrancoD; 10-28-2013 at 09:09 AM.
 
Old 10-28-2013, 09:18 AM   #4
johnsfine
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Registered: Dec 2007
Distribution: Centos
Posts: 4,962

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Quote:
Originally Posted by GianfrancoD View Post
Which is the size of char* b in asciitobinary() ?
You are probably hinting at the correct issue, but I think your hint is too subtle to be understood by someone who would make the original error.

Quote:
Originally Posted by pankaj8332 View Post
but not working
Pointers in C do not point anywhere usable unless your code makes them point somewhere usable.

If you just declare
char* b
it doesn't point to usable memory.

Quote:
for(k=j+7,j=j+7;k>=j;k--)
You also might want to think through the sequence of actions specified by that line.

Last edited by johnsfine; 10-28-2013 at 09:22 AM.
 
Old 10-28-2013, 09:35 AM   #5
pan64
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Registered: Mar 2012
Location: Hungary
Distribution: debian i686 (solaris)
Posts: 3,984

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also you may try to use debug info (compile with -g). in that case you will get much better error messages (instead of: assignment.c.text+0x1e)
 
Old 10-28-2013, 09:40 AM   #6
johnsfine
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Registered: Dec 2007
Distribution: Centos
Posts: 4,962

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Quote:
Originally Posted by pan64 View Post
also you may try to use debug info (compile with -g). in that case you will get much better error messages (instead of: assignment.c.text+0x1e)
You missed a change in the question. That original unclear error message was at link time, not run time and debug info would not have helped. That error was due to a typo the OP found and corrected without waiting from help from this thread.

The seg fault seems to be due to a basic misunderstanding of pointers in C. So debugging, to narrow down the moment at which the seg fault occurs, probably would not help.
 
  


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