?
Solved

Segmentation fault on char array bit wise operation

Posted on 2006-10-22
2
Medium Priority
?
309 Views
Last Modified: 2010-04-15
myFile.txt is a binary file:

Followed is the result of od -Ax -tx1 myFile.txt:
000000 68 01 00 00 a0 05 00 00 48 00 00 00 38 05 00 00

Followed is the complete code

#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>//O_RDONLY


int main(int argc, char *argv[])
{
     if (argc!=3){
          printf("Please enter exactly three arguments.\n");
     }else{
                 //myFile.txt is being memory map
          int f=open(myFile.txt,O_RDONLY);
          int n=lseek(f,0,SEEK_END);
          char * mf=mmap(0,n,PROT_READ,MAP_PRIVATE,f,0);
          int i;
          for (i=0;i<16;i++){
               mf[i]&=0x0F; //<--this gives me segmentation fault, what is the reason and how to correct it?
          }
         
     }

   return 0;
}



0
Comment
Question by:william007
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 45

Accepted Solution

by:
sunnycoder earned 2000 total points
ID: 17783433
>mf[i]&=0x0F;
Assigns it back to mf[i] which has been mmaped using PROT_READ
0
 
LVL 9

Author Comment

by:william007
ID: 17794375
Thanks=)
0

Featured Post

VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

An Outlet in Cocoa is a persistent reference to a GUI control; it connects a property (a variable) to a control.  For example, it is common to create an Outlet for the text field GUI control and change the text that appears in this field via that Ou…
Windows programmers of the C/C++ variety, how many of you realise that since Window 9x Microsoft has been lying to you about what constitutes Unicode (http://en.wikipedia.org/wiki/Unicode)? They will have you believe that Unicode requires you to use…
Video by: Grant
The goal of this video is to provide viewers with basic examples to understand and use nested-loops in the C programming language.
The goal of this video is to provide viewers with basic examples to understand and use switch statements in the C programming language.
Suggested Courses

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question