segmentation fault on assigning char to a char of a string at index

Hey folks sup!
I have a segmentation fault here:

Code:

---

char * inttobinstr(int n)
{
        char *binstr;
        binstr = (char*)malloc(sizeof(char)*8);
        binstr = "00000001";
        binstr[6]='s';  <---------this assignment gives me the error
        return binstr;
}

---

what could be the problem??

Actually it appears in this line

Code:

---

binstr = "00000001"; /* goes out of bounds because binstr needs space for 9 chars due to null terminator */

---

Quote:

---

Originally Posted by itCbitC

Actually it appears in this line

Code:

---

binstr = "00000001"; /* goes out of bounds because binstr needs space for 9 chars due to null terminator */

---

---

Incorrect.

binstr will now point to the address of "00000001", and binstr[6] is assigning +6 past this already read-only address.

You cannot modify string literals, and by assigning the address of "00000001" to binstr you have leaked the memory you allocated using malloc().

Quote:

---

Originally Posted by zacs7

Incorrect.

binstr will now point to the address of "00000001", and binstr[6] is assigning +6 past this already read-only address.

---

Dang! you're right, didn't notice no square brackets :eek:

so how to solve this problem?
ok... if i declare it as an array of char like char binstr[8]="00000000";
then i want to return pointer to that string....

Quote:

---

Originally Posted by r00t

so how to solve this problem?
ok... if i declare it as an array of char like char binstr[8]="00000000";
then i want to return pointer to that string....

---

Why not just copy the string into the memory you allocated with malloc()? Note that "00000000" takes 9 bytes (including the null terminator) not 8 bytes.

Or just pass in a pointer as an argument, and let the caller supply the memory. For example:

Code:

---

void inttobinstr(const int n, char * str, size_t size)
{
  ...
}

---

but the problem is occuring on the line i marked red....why is that happening? i couldn't get it...

Quote:

---

Originally Posted by r00t

but the problem is occuring on the line i marked red....why is that happening? i couldn't get it...

---

You cannot modify string literals, the standard dictates that doing so is implementation defined.

"00000001" in this case is a string literal, you are assigning its address to 'binstr' and by setting binstr[6] to 's' you are modifying the string literal. Your implementation defines this as illegal (or doesn't define behaviour at all), hence the segmentation fault.

ah ok thnx, i'll try to pass it as you wrote..