More arcane knowledge that I've never used, but find useful: C defines an offsetof() macro, used to find the offset in bytes of a member within a struct or union. Modern compilers have a built-in function to do this, with the macro pointing there, to avoid the traditional macro:
#define offsetof(st, m) ((size_t)(&((st *)0)->m))
In response to 'Goto Considered Harmful', some enterprising folks created a COMEFROM.
123 | 10 COMEFROM 30
20 PRINT "HELLO WORLD"
30 REM
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Interestingly enough, this is somewhat similar to debug hooks / breakpoints today.
I had assumed simpler code for access -> faster access; this is one of the many things I learned in java that I am relearning/refreshing for C++.
Summary: using iterators is faster than any other method of access (that I know of).
Reference
Quote: The following code is the fast inverse square root implementation from Quake III Arena, stripped of C preprocessor directives, but including the exact original comment text:
12345678910111213141516 | float Q_rsqrt( float number )
{
long i;
float x2, y;
const float threehalfs = 1.5F;
x2 = number * 0.5F;
y = number;
i = * ( long * ) &y;
i = 0x5f3759df - ( i >> 1 );
y = * ( float * ) &i;
y = y * ( threehalfs - ( x2 * y * y ) );
return y;
}
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Here's a good explanation I found at betterexplained.com.