copying value of void pointer C - c

Question

I have a problem with function which should print any type of integer on my KS0108 lcd. Here the problem is: when i want to copy void* numb value to void* temp in first swtich - nothing happens. in second switch when use %I get 0. (value of void* numb is about 48 and type _uint8_t)
Code:
void glcd_WriteInt(void* numb, type type)
{
void* temp = 0;
int8_t buff[10];
int8_t size = 0;
int8_t flag = 1;
int8_t sign = 1;
switch(type)
{
case _int8_t: memcpy(temp, numb, sizeof(int8_t)); break;
case _int16_t: memcpy(temp, numb, sizeof(int16_t)); break;
case _int32_t: memcpy(temp, numb, sizeof(int32_t)); break;
case _int64_t: /*memcpy(temp, numb, sizeof(int64_t)); break;*/return; //if want 64 - uncomment
case _uint8_t: *(uint8_t*) temp = *(uint8_t*) numb/*memcpy(temp, numb, sizeof(uint8_t))*/; break;
case _uint16_t: memcpy(temp, numb, sizeof(uint16_t)); break;
case _uint32_t: memcpy(temp, numb, sizeof(uint32_t)); break;
case _uint64_t: /*memcpy(temp, numb, sizeof(uint64_t)); break;*/return; //if want 64 - uncomment
}
while(flag)
{
switch(type)
{
case _int8_t:
buff[size] = *(int8_t*) temp % 100;
flag = (*(int8_t*) temp /= 100) != 0;
break;
case _int16_t:
buff[size] = *(int16_t*) temp % 100;
flag = (*(int16_t*) temp /= 100) != 0;
break;
case _int32_t:
buff[size] = *(int32_t*) temp % 100;
flag = (*(int32_t*) temp /= 100) != 0;
break;
case _int64_t:
/*buff[size] = *(int64_t*) temp % 100; //if want 64 - uncomment
flag = (*(int64_t*) temp /= 100) != 0;*/
break;
case _uint8_t:
buff[size] = *(uint8_t*) temp % 100;
flag = (*(uint8_t*) temp /= 100) != 0;
break;
case _uint16_t:
buff[size] = *(uint16_t*) temp % 100;
flag = (*(uint16_t*) temp /= 100) != 0;
break;
case _uint32_t:
buff[size] = *(uint32_t*) temp % 100;
flag = (*(uint32_t*) temp /= 100) != 0;
break;
case _uint64_t:
/*buff[size] = *(uint64_t*) temp % 100; //if want 64 - uncomment
flag = (*(uint64_t*) temp /= 100) != 0;*/
break;
}
if(buff[size] < 0){
buff[size] = -buff[size];
sign = -1;
}
size++;
}
if(sign == -1) glcd_Character((char) 45);
glcd_WIntTab(buff, size);
}
I tried versions with memcpy, and like here: casts. It is suprising that this function was OK a few days ago.

Answer 1

Your main problem is that you have
void *temp = 0;
declared, and you try to write to a NULL pointer since you initialize it with void *temp = 0.
Even if you don't initialize it, it wont work because it wouldn't be a valid pointer, so either you allocate memory with malloc and assign it to the void *temp pointer, or use a union this way
union Type {
int8_t _int8_t;
int16_t _int16_t;
int32_t _int32_t;
int64_t _int64_t;
uint8_t _uint8_t;
uint16_t _uint16_t;
uint32_t _uint32_t;
uint64_t _uint64_t;
};
void glcd_WriteInt(void* numb, enum type type)
{
union Type temp;
int8_t buff[10];
int8_t size = 0;
int8_t flag = 1;
int8_t sign = 1;
switch (type)
{
case _int8_t: memcpy(&temp, numb, sizeof(int8_t)); break;
case _int16_t: memcpy(&temp, numb, sizeof(int16_t)); break;
case _int32_t: memcpy(&temp, numb, sizeof(int32_t)); break;
case _int64_t: /*memcpy(&temp, numb, sizeof(int64_t)); break;*/return; //if want 64 - uncomment
case _uint8_t: memcpy(&temp, numb, sizeof(uint8_t))/*memcpy(temp, numb, sizeof(uint8_t))*/; break;
case _uint16_t: memcpy(&temp, numb, sizeof(uint16_t)); break;
case _uint32_t: memcpy(&temp, numb, sizeof(uint32_t)); break;
case _uint64_t: /*memcpy(&temp, numb, sizeof(uint64_t)); break;*/return; //if want 64 - uncomment
}
while (flag)
{
switch (type)
{
case _int8_t:
buff[size] = temp._int8_t % 100;
flag = (temp._int8_t /= 100) != 0;
break;
case _int16_t:
buff[size] = temp._int16_t % 100;
flag = (temp._int16_t /= 100) != 0;
break;
case _int32_t:
buff[size] = temp._int32_t % 100;
flag = (temp._int32_t /= 100) != 0;
break;
case _int64_t:
buff[size] = temp._int64_t % 100;
flag = (temp._int64_t /= 100) != 0;
break;
case _uint8_t:
buff[size] = temp._uint8_t % 100;
flag = (temp._uint8_t /= 100) != 0;
break;
case _uint16_t:
buff[size] = temp._uint16_t % 100;
flag = (temp._uint16_t /= 100) != 0;
break;
case _uint32_t:
buff[size] = temp._uint32_t % 100;
flag = (temp._uint32_t /= 100) != 0;
break;
case _uint64_t:
buff[size] = temp._uint64_t % 100;
flag = (temp._uint64_t /= 100) != 0;
break;
}
if (buff[size] < 0)
{
buff[size] = -buff[size];
sign = -1;
}
size++;
}
if (sign == -1)
glcd_Character((char) 45);
glcd_WIntTab(buff, size);
}
I believe the union is a better solution.