c - Segmentation fault occurring when modifying a string using pointers? -

-

context

I am learning C, and I want to reverse the string using a space I'm trying to give the hints. (I know that you can use an array, it is more about learning about pointers.)

problem

While trying to run code below I'm getting split error. It looks like * end = * start; Not like the line Why is that so?

Especially when my code is almost identical 

  #include & lt; Stdio.h & gt; #include & lt; String.h & gt; Zero my_strrev (four * start) {char temp; Four * end; End = begin + strlen (start) - 1; While (end> started) {temp = * end; * End = start * * Start = temporary; End--; ++ start; }} Main () {char * string = "foobar"; My_strrev (string); Printf ("% s", string); }   
 
 
 One problem is that with the parameter passing the function: < / P> 
  char * string = "foobar";  
 
 This is a fixed string allocated in the read-only part. 
 
  * end = * starts when you try to overwrite it;  
 
 You will receive segfault. 
 
 Try 
 
  Four String [] = "foobar";  
 
 And you should notice the difference. 
 
 The main point is that in the first case, the string is present in the read-only segment and is simply an indicator on it in the second case while the array of characters with appropriate size has been reserved on the pile and fixed The string (which is always present) is copied to it. After that you are free to modify the contents of the array.

Comments

Post a Comment

Popular posts from this blog

oracle - The fastest way to check if some records in a database table? -

-
I have a big table to work with. I have to see that there are some records whose parent_id is equal to my passing value. Currently I do this by implementing "my_table using select count (*) where parent_id =: id"; If the result> 0, it means that they exist. Because this is a very large table, and I do not care what the actual number of records present, I just want to know if it exists, so I think count (*) Bit is disabled. How do I apply this requirement most quickly? I'm using Oracle 10. # Tips for Hibernation & amp; Tricks It suggests writing in such a way: Integer number = (integer) session .createQuery ("Select Count (*) to ...."). UniqueResult (); I do not know what is the magic of the unique rule? Why does it fast? To compare, select "1 from mytable where parent_id = passId and rowrum", which is more efficient? If you are not interested in the number of records, then there is an EXISTS query one: Select 'y'
Read more

php - multilevel menu with multilevel array -

-
Just ask someone to solve this problem? I want to create a multilevel menu I can not find the right solution generated with multilevel array, it always gets an array_push error My study came from the original idea But still my Can not match the need. This is my MySQL [code] ----- --------------------- --------------- | ID | PARENT_ID | Name | Link | Seq | 1 | 0 | Dashboad | Dashboard / | 1 | 2 | 0 | Menu 1 | Menu 1 / | 2 | 3 | 0 | Menu 2 | Menu 2 / | 3 | 4 | 0 | Menu 3 | Menu 3 / | 4 | 5 | 2 | Joint Add / | 1 | 6 | 3 | Joint Add / | 1 | 7 | 2 | Edit | Edit / | 2 | 8 | 4 | Joint Add / | 1 ------------------------------------------ [/ Code] I want to do something like this in my array array ('dashboard' = & gt; array ('id' = & gt; '' 'Dame' = & gt; 'Dashboard', 'Title' = & gt; 'Dashboard', 'MatchMin' = & gt; Base_URL (). 'Dashboard /', 'Active' => = & Gt; NULL), &
Read more

jQuery UI: Datepicker month format -

-
I am trying to change the format of the month that shows in the popup (not in the date that the picker actually I do not have any choice anywhere to do this, do I like to use a sub-string () or something else? What I normally display is Trying to change: Class = "ui-datepicker-title"> January & lt; / span & gt; ... & lt; / div & gt; Div>
Read more