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error c2664 'memcpy' : cannot convert parameter 1 from 'int' to 'void *'

nukem266 (25)
Hi little new to c++, hope I am in the right section.

I researched the error code and its obviously to do with my data types, but because I am using enums I have gotten a little confused and not sure how to define the problem any further and or how to fix it.

When compilingi get the error below:

main.cpp(186) : error C2664: 'memcpy' : cannot convert parameter 1 from 'int' to
'void *'
Conversion from integral type to pointer type requires reinterpret_cast,
C-style cast or function-style cast

Any advice would be greatly appreciated, the line number wont be the same seen as a lot of commented out code I did not copy over.

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#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <conio.h>
#include <malloc.h>

#define MAX_PROG_SIZE		20
#define MAX_PROG_OVERFLOW	40

#define Randint(UPPER) ((int)(random_number()*(UPPER)))

enum tokens {DUMMY, LEFT, RIGHT, MOVE, IF_FOOD_AHEAD, PROGN2, PROGN3, GHOST_NODE};

struct token_entry
{
   char *name;
   int arity_sub1;
   // function
};

struct token_entry token_table [] =
     { {"# ", -1},     // String end. Arity must be -1 for sub-string search
       {"LEFT ", -1},
       {"RIGHT ", -1},
       {"MOVE ", -1},
       {"IF_FOOD_AHEAD ", 1},
       {"PROGN2 ", 1},
       {"PROGN3 ", 2},
	   {"GHOST_NODE", -1}
     };

int main()
{
	int editdistance = 0;
	int i;
	int ar1 = 0; 
	int ar2 = 0;
	int a, b, j, x = 0;

	int s1[MAX_PROG_SIZE]={4, 5, 1, 6, 1, 2, 3, 3 };
	int s2[MAX_PROG_SIZE]={5, 1, 5, 2, 5, 4, 3, 1, 3};
	int c[MAX_PROG_OVERFLOW]={};
	int g[1]={7};
	
for ( i = 0; i < MAX_PROG_SIZE ; i++ )
{
	printf("s1 %d and s2 %d\n", s1[a],s2[b]);
		
  if (s1[a] != s2[b])
  {
	  printf("The edit distance is now %d\n", editdistance);
	  editdistance = editdistance + 1;
	  printf("The edit distance has increased to %d\n\n", editdistance);
  }
  else if (s1[a] == s2[b])
  {
	  printf("The edit distance is %d\n\n", editdistance);
  }
  else if (s1[a] == NULL)
  {
	  ar1 = 0;
  }
  else if (s1[b] == NULL)
  {
	  ar2 = 0;
  }
  
  printf("The edit distance is now %d\n", editdistance);

	switch( s1[a] )
		{
			case LEFT : // LEFT
				ar1 = 0;
				printf("I have got here, ar1 = %d\n", ar1);
					break;
			case RIGHT : // RIGHT
				ar1 = 0;
				printf("I have got here, ar1 = %d\n", ar1);
					break;
			case MOVE : // MOVE
				ar1 = 0;
				printf("I have got here, ar1 = %d\n", ar1);
					break;
			case IF_FOOD_AHEAD : // IF_FOOD_AHEAD
				ar1 = 2;
				printf("I have got here, ar1 = %d\n", ar1);
					break;
			case PROGN2 : // PROGN2
				ar1 = 2;
				printf("I have got here, ar1 = %d\n", ar1);
					break;
			case PROGN3 : // PROGN3
				ar1 = 3;
				printf("I have got here, ar1 = %d\n", ar1);
					break;
			case GHOST_NODE : // GHOST_NODE
				ar1 = 0;
				printf("I have got here, ar1 = %d\n", ar1);
					break;
			default :
				ar1 = 0;
				break;
			}
			switch( s2[b] )
			{
			case LEFT : // LEFT
				ar2 = 0;
				printf("I have got here, ar2 = %d\n", ar2);
					break;
			case RIGHT : // RIGHT
				ar2 = 0;
				printf("I have got here, ar2 = %d\n", ar2);
					break;
			case MOVE : // MOVE
				ar2 = 0;
				printf("I have got here, ar2 = %d\n", ar2);
					break;
			case IF_FOOD_AHEAD : // IF_FOOD_AHEAD
				ar2 = 2;
				printf("I have got here, ar2 = %d\n", ar2);
					break;
			case PROGN2 : // PROGN2
				ar2 = 2;
				printf("I have got here, ar2 = %d\n", ar2);
					break;
			case PROGN3 : // PROGN3
				ar2 = 3;
				printf("I have got here, ar2 = %d\n", ar2);
					break;
			case GHOST_NODE : // GHOST_NODE
				ar2 = 0;
				printf("I have got here, ar2 = %d\n", ar2);
					break;
			default :
				ar2 = 0;
				break;
			}
		
if ((ar1 - ar2) > (ar2 - ar1))
	{
	int k = 0;
		memcpy(c[k], s2[b+1], MAX_PROG_SIZE + 1); // This line is the one causing the problems
		printf("Memcpy complete s2\n");
	}
	
	a++;				
	b++;

	}
getch();
return 0;
}


As you can see above I am trying to cope the tail of array s2[b+1] to an empty array c[k], I am a little clueless any information would be greatly appreciated also any code improvements would be welcomed.

PS. If I am in the wrong thread please let me know where to post it so I can get a response.
rcast (354)
Starting at line 40, are a and b, not yet initialized?

Line 40:
 
 
int a, b, j, x = 0; // only x is initialized


Should be:
 
 
int a = 0, b = 0, j = 0, x = 0;
Last edited on
Chervil (7320)
True, a and b are defined (that is memory has been allocated) but not initialised (assigned any specific value).

You can get the code to compile by doing this:
 
 
    memcpy((void *) &c[k], (void *) &s2[b+1], MAX_PROG_SIZE + 1);

but I've not verified whether this actually makes sense.

toum (353)
Your use of memcpy does not make sense.
What are you trying to do ? Something like c[k] = s2[b+1];?
nukem266 (25)
@rcast sorry the variables were different before i was playing with them must of broken them but i fixed them again i was trying to optimise and it broke, should of left it the way it was.

int a = 0;
int b = 0;
int j = 0;
int x = 0;

Want to use it your way but didn't know how.

@ Chervil thank you that seems to have fixed the error on compile, i tried putting void * in but didn't know the correct syntax or the reason for it. Does the & symbol refer to what you are using?

@Toum something like that but a bit more in-depth i am creating a function for genetic programming.

Thank you for all your help.
Last edited on
Chervil (7320)
The & symbol gives the address of the object. In this case, the object is an element of the array, so it gives the address part-way into the array.
nukem266 (25)
Ahh excellent and the void * just means that there is no specific data type? or am i wrong?

Really appreciate the help no idea why i didn't post sooner been stuck on this for days.
Chervil (7320)
without the (void *), the & gives a pointer to an int. It needs to be cast to a void type (non-specific) as that is what is expected by function memcpy().

http://www.cplusplus.com/reference/cstring/memcpy/
nukem266 (25)
Thank you i understand it now, Ii read over that page a few times just didn't sink in. Plus the way you wrote the line is slightly different still I have to much to learn, thank you very much.
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