How to extract address from c-string

Question

I'm writing my program and i need to get a pointer from c-string. For example, i have a string like "0x3b021e01" and as an output i want a legal pointer void *ptr == 0x3021e101.

I tried this approach:

char *addr = "0x3021e101"; // this address is just an example of 32-bit addr

uint32_t iaddr = from_ch_to_hex(addr); // iaddr == 0x3021e101

void *data_buf = (void *)iaddr; // data_buf = 0x3021e101

uint32_t reg_val = *(uint32_t *)data_buf;

But I get Segmentation fault. What's wrong here? How can i fix it?

Well, is it a legal uint32_t address? It doesn't look right - alignment wrong. — Martin James, Nov 09 '13 at 19:53
Hang on - the address is more than 32 bits. Is this a 64-bit pointer? — Martin James, Nov 09 '13 at 19:57
OK, now it's clearer. Does your architecture and/or memory-manager support access to non-aligned memory addresses? — Martin James, Nov 09 '13 at 20:00
Even more interesting - is this code running on the debugger server or remote client? — Martin James, Nov 09 '13 at 20:02
Yeah, it looks as if the problem is in alignment. It's running on the server. Thanks! — , Nov 09 '13 at 20:14

score 1 · Accepted Answer · answered Nov 09 '13 at 19:53

1

0x3b021e101 is an odd number, so you would expect alignment errors.

By the way, unless you know by other means that the address is valid, say by having a pointer to that address, why don't you just use that pointer?

answered Nov 09 '13 at 19:53

Charlie Burns

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How to extract address from c-string

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