nested loops to streamlined code

[ajetrumpet]

all,

in C++ right now, I have code similar to this (symantics may not be right, just ignore it. Example came from PHP):

        If (ctr = 4) {
          for (block = 1; block <= 27; block += 3) {
            for (ctr2 = 1; ctr2 <= 3; ctr2++) { //each line.
              for (ctr3 = 1; ctr3 <= 3; ctr3++) { //char 1 - 3 in each line.
                switch (ctr2) { //which line?
                  Case 1:
                    strOut = strOut . substr(Line1, block - 1 + ctr3, 1);
                  Case 2:
                    strOut = strOut . substr(Line2, block - 1 + ctr3, 1);
                  Case 3:
                    strOut = strOut . substr(Line3, block - 1 + ctr3, 1);
                }
              }
            }
          }
        }

I don't have a spreadsheet or anything set up to where I can identify all internal resources that C++ has to streamline this, either by mathematical means or method means.

can someone help me here in that regard? anyone know how can this be consolidated using C++ resources?

I never like writing long iterations, but as it just so happens, this can be done very rapidly without having to re-learn any given language with the purpose of using cleaner/better coding techniques.

any help appreciated. thanks.

[Coder Dave]

You could take the switch statement outside of the third loop. That should speed it up a tiny bit. Also, since loops two and three only get iterated three times, you could unroll them to get better performance.

	if (ctr == 4)
	{
		for (block = 1; block <= 27; block += 3)
		{
			strOut = strOut . substr(Line1, block, 1);
			strOut = strOut . substr(Line1, block + 1, 1);
			strOut = strOut . substr(Line1, block + 2, 1);
			strOut = strOut . substr(Line2, block, 1);
			strOut = strOut . substr(Line2, block + 1, 1);
			strOut = strOut . substr(Line2, block + 2, 1);
			strOut = strOut . substr(Line3, block, 1);
			strOut = strOut . substr(Line3, block + 1, 1);
			strOut = strOut . substr(Line3, block + 2, 1);
		}
	}

From further analysis this could be simplified to

	if (ctr == 4)
	{
		for (block = 1; block <= 27; block += 3)
		{
			strOut = strOut . substr(Line1, block, 3);
			strOut = strOut . substr(Line2, block, 3);
			strOut = strOut . substr(Line3, block, 3);
		}
	}

You could also eliminate the multiple calls to the string concatenate function, which may be reallocating memory each time, by using a fixed array of 81 characters, filling that with the substrings, and then concatenating that to the output string.