Re: (part 5) Han from China answers your C questions

Ben Bacarisse <ben.use...@xxxxxxxxx> wrote:
Borked Pseudo Mailed <nob...@xxxxxxxxxxxxxxxxx> writes:
a question abou "atoi" 66650...@xxxxxx said:
First,thanks for all who have answered my last question.

if                    char string[20]="12345";

how could I convert the string[2](that is "3") to an
int by using atoi? I only want to convert string[2],not
other string[i].

    int a;
    char string[20]="12345";
    atoi((a=string[2]-'0',"X"));

The consensus is

"You don't vote for kings!"
- King Arther - Monty Python's Holy Grail

that this exhibits undefined behaviour
(quite apart from being silly).

Silly, yes, ub no. Note: atoi("X") produces 0. UB occurs
if (and only if) strtol(blah, 0, 10) would produce a value
outside the range of int.

 If the OP really needs to use atoi to do this
simple conversion,

The OP doesn't, so why entertain the possibility? ;)

--
Peter
.

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