Why this dies

[Tubs]

code:

#include <stdio.h> #define PATH "/usr/tmp" char *full_name(const char name[]); int main() {   printf("Full name is %s\n", full_name("data"));   system ("PAUSE");   return (0); } char *full_name(const char name[]) {   static char file_name[100];   strcpy(file_name, PATH);   strcat(file_name, '/');   strcat(file_name, name);   return(file_name); }

Why does this program die a horribly gruesome death?

[wtd]

code:

#include <stdio.h> #define PATH "/usr/tmp" char *full_name(const char* name); int main() {   printf("Full name is %s\n", full_name("data"));   system("PAUSE");   return 0; } char *full_name(const char* name) {   char* file_name = malloc(sizeof(char) * 100);   strcpy(file_name, PATH);   strcat(file_name, "/");   strcat(file_name, name);   return file_name; }

What did I do differently?

[Tubs]

Changed the parameter to a pointer and dynamically allocated memory for the variable?

[Tubs]

that code is giving me errors!!! line 19 makes a pointer from integer without a cast

[wtd]

Yes, returning a pointer to stack-allocated memory inside a function results in bad things happening.

I don't get any such error using GCC. Show me the exact code you were using.

[Tubs]

wtd wrote:

Yes, returning a pointer to stack-allocated memory inside a function results in bad things happening.

I don't get any such error using GCC. Show me the exact code you were using.

The one you posted.

[wtd]

Then I cannot help. The code I posted compiles flawlessly with GCC 3.4.2 (MinGW).

[Tubs]

Ok, I got the code working. IDEs are foolish.

Another question: how would I go about making a function that finds a certain item in a linked list, given the number it is in order and a pointer to the beginning of the list? This is what I have so far:

code:

#include <stdio.h> #include "coaster_info_t.h" coaster_info_t find_nth_coaster (int *N, int index) {   coaster_node_t *current = *N;   int i = 0;   if (current != NULL && i != index)     current = current->next;   else if (current != NULL && i == index)     return( current );   else     return ( NULL ); }

[wtd]

Use a loop to follow the links?

[Tubs]

Yeah, thanks. New question if I may:

A sequence is defined by the following recursive relationship:

A(n) = A(n/2) + A(n/2) ; A(1) = 3

It is defined only for powers of 2 and you need only consider powers of two.

I don't think I know what they are asking here, this is my code so far:

code:

#include <stdio.h> int A (int n); int main(int argc, char *argv[]) {   int n, x;   printf ("n = ");   scanf ("%d", &n);   printf ("\n");   x = A (n);   printf ("A (n) = %.2f\n", x);   system ("pause");   return 0; } double A (double n) {   if (n == 1)     return n;   else     n = A (n / 2) + A (n / 2); }

Help greatly appreciated

[wtd]

Look at that code really closely.

Now... remove all of the code inside the functions, leaving just the headers? See the problem?

[Tubs]

wtd wrote:

Look at that code really closely.

Now... remove all of the code inside the functions, leaving just the headers? See the problem?

Yeah, I was fooling around with the types because the question seemed to imply that that ints were ok, but there is division by 2 thrown in there. When I change it to double type it outputs 0, when it is an integer, 1. I'm still lost.

[wtd]

What they're saying is... when n is 1, A returns 3. For any other value of n, well... the question explains that. So, let's look at a breakdown of A(8).

code:

A(8) A(4) + A(4) (A(2) + A(2)) + (A(2) + A(2)) ((A(1) + A(1)) + (A(1) + A(1))) + ((A(1) + A(1)) + (A(1) + A(1))) A(1) + A(1) + A(1) + A(1) + A(1) + A(1) + A(1) + A(1) 3 + 3 + 3 + 3 + 3 + 3 + 3 + 3 24

[Tubs]

Thanks a lot wtd. You rock.

[wtd]

Glad I could help.

code:

(defun a (&optional (n 1))   (cond ((= n 1) 3)         ((> n 1)          (let ((v (a (/ n 2))))            (+ v v)))         (t          (let ((v (a (* n 2))))            (+ v v)))))