Re: Using printf in C++
On 21/05/2012 03:38, Pavel wrote:
Now that I thought of it more, the case seems to be deserving deeper
analysis (I myself was a moderate proponent of exceptions before and now
I am having a second thought). This is because the exception-based
method of error reporting seems to break one of the declared principles
of C++ design: you only pay for the features you use. From this
viewpoint, this is what concerns me:
There are some cases in which error reporting via exceptions is
essential to make the code *faster* than non-exception-based
alternatives, for example:
while (i < N) {
__try {
for (; i < N; i++)
a[i] = log(b[i] * c[i]); // floating point math
} __catch(exCode() == OVERFLOW) { // overflow ex. from the hw
a[i] = log(b[i]) + log(c[i]); // redo without overflow
++i;
}
}
There the time to make support for the exception handling is negligible,
since there is only one function call in the critical loop. The
exception is costly, when it occurs, but we assume that the occurrence
is rare.
Alternatives to look for errors are less efficient, for example checking
for overflow inside the loop requires two floating point comparisons,
which make the solution relatively costly; while using log(a[i]) +
log(b[i]) directly would double the number of calls to log().