将char数组转换为C中的void *指针

Question

I want to read an address ( Like 0x827483 ) from input, and save this address in a void * variable. first i make this address as long long variable:

while(c != ' ' && !feof(file))
{
    if('0' <= c && c <= '9')
        num = c - '0';
    else if('a' <= c && c <= 'f')
        num = c - 'a' + 10;
    b = b * 16 + num;
    c = fgetc(file);
    s[i++] = c;
}

and then i cast it to void *.

void * adr = (void *) b;

my code is working, but i got warning.

What can i do?

Answer 1

The warning is telling you the long long integer and the void * are different sizes. Most likely, the long long is 64 bit while the void * is 32 bit.

If you only need to build 32 bit code then you can use void * adr = (void *)(long)b .

I think a better solution is to use uintptr_t instead of long long . That will insure the sizes are compatible for both 32 and 64 bit code.

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As a side note, reading a memory address from a file is an insecure and dangerous practice. You need to validate that the pointer is something useful before you use it in any way.