C / C++ / MFC

int calc(int var) {
	//try convert short to int
	int tmp = var + 30003;

    return tmp;
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

void calc(char *type, void *var1, char calc, void *var2) {

int tmp1 = *(int*)var1;//bad
int tmp2 = *(int*)var2;//bad
/*//this "work" but i want these short converted to int
short int tmp1 = *(short int*)var1;
short int tmp2 = *(short int*)var2;*/
printf("tmp1: %i\n", tmp1);
printf("tmp2: %i\n", tmp2);

int max, min;
unsigned int umax, umin;
short int overflow = 0;

if(strncmp(type, "short int", 9)==0) {
	max = SHRT_MAX;
	min = SHRT_MIN;
	}

if(calc == '+') {
	/*
	if(overflow == 0) {
		*(short int*)var1 = *(short int*)var1 + *(short int*)var2;
		}
	else{
		//addition not in short range, so cast the original var
		*(int*)var1 = tmp1 + tmp2;
		}
	*/
	}
}

int main() {
	short int vInt2 = 32767;//i dont know what is his real value at the moment, maybe in a loop
	short int vInt3 = 1;
	calc("short int", &vInt2, '+', &vInt3);
	printf("bad convert to int: %i\n", vInt2);
    return 0;
}

void calc(void* pvoid)
{
    int value = *(int*)pvoid:
    // what happens if pvoid points to a floating point value?
}

luplup wrote:

You too you misunderstood my problem i think,

luplup wrote:

Never i will go back in this forum

luplup wrote:

Never i will go back in this forum

luplup wrote:

Edit: So if i dont use void, it seems i have to write lot of calc "identical" function for each type....

luplup wrote:

Do i have to use calloc/realloc for the int too ? like i used it for the char/struct array.

luplup wrote:

So please can you show me the right way to cast correctly

1. Could you explain what are you trying to achieve using such type of very dangerous castings?

2. luplup wrote:

   void calc(void *var) {
   //try convert short to int with new var
   int tmp = (int)var;
   printf("tmp: %i\n", tmp);//bad, must be 30002
   //try cast/convert original var
   (int)var += 30003;
   }

   
   The problem with this "casting" is the origin of the parameter passed to is short integer (the low WORD in Win32 environment).
   But you are then trying to interpret it (somehow) as int causing to take into account the high WORD which contain garbage!
   So what do you expect from the next manipulations with this garbage?

int tmp = (short int)var;

luplup wrote:

is this a valid cast short to int ?

C++

int tmp = (short int)var;