...memcpy from the  src

memcpy( foo, bar, len );

(inlined if optimised for speed, either way...

...x[len >> 5] |= 0x80 << (24 - len % 32);
-  x[(((len + 65 + 511) >> 9) << 4) - 1] = len...

...len;

    len = out_string.length;
    WriteFile(fd,            // handle to file
                     out_string,   // data buffer
                     len...

...len;

	len = out_string.length;
	WriteFile(fd,            // handle to file
		 out_string,   // data buffer
		 len...

...its length, why not:

a[n:len];
a[n#len]; // arguably better - kinda looks like...

...1)
a[n..n+len] creates a slice of length 'len'
much the same as...

...str[1024];
    int len;
    int s;

    fgets(str,sizeof(str),stdin);
    len = strlen(str);

    for...

...same as
void fn(int *a, int len)
Effectively you cannot resize the array inside...

...in C++:  void fn(int *a, int len);
in D:       void fn(in int[] a...

...len=0; while (*s++) ++len; return len;  // error... can't modify
parameter "s"
    uint len...