On Wednesday, 19 July 2017 at 13:30:56 UTC, sontung wrote:
So I was thinking of a way of extending if statements that have
declarations. The following being as example of the current use
of if statements with declarations:
if(int* weDontPollute = someFunc())
{
// use weDontPollute
}
That's great and all, but it only works by checking if the
variable evaluates to true or false. Which is fine for a
pointer but otherwise useless for anything else, like integers
where zero is usually valid input (index for array). So
currently the only way to do something like this in the
language, that i've found, is to use a for statement.
for(int i = someFunc(); i >= 0;)
{
// use i
break;
}
Not that ideal to use a for statement. It makes it hard to read
and if the break condition isn't there it might very well be an
infinite loop. So I was thinking of some sort of syntax like
this:
if(int i = someFunc(); i >= 0)
{
// use i
}
Thoughts on this sort of feature?
This is included in C++17:
http://en.cppreference.com/w/cpp/language/if
```
int demo() {
if (auto it = m.find(10); it != m.end()) { return it->size(); }
if (char buf[10]; std::fgets(buf, 10, stdin)) { m[0] += buf; }
...
```
