how to avoid compilation error: expression must be a modifiable lvalue
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Hi.
I met a compilation error with following code. a physical buffer (communication buffer of MCU) tossed to void* dest. if I change all argument to local variable and pointer compilation successful.
First I thought, polyspace doesn't understand typecasting of void to other, but I guess now when physical address is tossed as argument then it occur compilation error "expression must be a modifiable lvalue", since polyspace doesn't understand physical address.
Am i thinking correct? and does anybody can help me to avoid compilation error?
typedef unsigned char u08;
void* AL_MemCpy (void* dest, const void* source, u08 count)
{
while (count--)
{
*((u08*)dest)++ = *((u08*)source)++;
}
}
// used in other function like below
(void)AL_MEMCPY(RxBuffer,&(data[1]),(u08)RxMessage.Length);
采纳的回答
(u8 *) dest is a temporary variable, which cannot be increased. Perhaps you want this:
*((u08*)dest++) = *((u08*)source++);
But this copies the first byte only. Perhaps memcpy would be smarter?
Or:
u08 *d = (u08 *) dest, *s = (u08 *) source;
while (count--) {
*d++ = *s++;
}
2 个评论
James Tursa
2013-1-17
编辑：James Tursa
2013-1-17
+1 is for the last option shown, which I prefer since it is clear what is being done and avoids trying to apply the ++ operator to a (void *) type (which inherently doesn't make sense and isn't allowed since void is of unknown size) using fancy-mangled syntax (e.g., the first option shown above will not compile).
Bong-Kee Choi
2013-1-17
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2013-1-17
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