What is this?

[helios]

I just found this source in the office. I probably copied it from someone's post here to test it. Can anyone figure out what it does?

#include <iostream>
#include <string>
#include <ctime>
#include <cstring>

#if 1
typedef char char_t;
#else
typedef wchar_t char_t;
#endif

typedef std::basic_string<char_t> str_t;

const size_t size = 1 << 21;

std::string replace(const std::string &s, const char_t *what, const char_t *with){
	std::string ret;
	ret.reserve(s.capacity());
	size_t len1 = strlen(what);
	size_t len2 = strlen(with);
	ret.resize(ret.size() * len2 / len1);
}

int main(){
	clock_t t0 = clock();
	str_t string;
	size_t size2 = size * 8 / 7;
	size2 = size2 + size2 / 90 * 2;
	string.reserve(size2);
	const unsigned N = 1000;
	for (int n = 0; n < N; n++){
		string.resize(size, '-');
		char_t *p = &string[0];
		size_t length = string.size();
		for (size_t i = 6; i < length; i += 7)
			p[i] = 'P';
		length = length * 8 / 7;
		string.resize(length);
		p = &string[0];
		for (size_t i = length; --i;)
			p[i] = p[i - i / 8];
		for (size_t i = 7; i < length; i += 8)
			p[i] = 'U';
		
		length += length / 90 * 2;
		string.resize(length);
		p = &string[0];
		for (size_t i = length; --i;)
			p[i] = p[i - i / 92 * 2];
		
		for (size_t i = 90; i < length; i += 92)
			p[i] = 13;
		for (size_t i = 91; i < length; i += 92)
			p[i] = 10;
	}
	clock_t t1 = clock();
	std::cout <<double(t1 - t0) / (double)CLOCKS_PER_SEC * 1000.0 / N<<std::endl;
	std::cout << string << std::endl;
}

[28poGNh0]

I think we cure cancer with this code !

[28poGNh0]

for (size_t i = 90; i < length; i += 92)
	p[i] = 13;
for (size_t i = 91; i < length; i += 92)
	p[i] = 10;

Doesn't make any sence

First loop :
Well lets fill some of p array element with the number 13

second loop :
Sorry lets fill them with 10 ,except the p[90] !!!!!

[helios]

Read it more carefully. It's setting to 13 every p[i] where i % 92 == 90, and to 10 every p[i] where i % 92 == 91. In other words, it makes sure that there's a CRLF sequence at least once every 92 characters (including the sequence itself).

[MiiNiPaa]

Behold the power of Google: http://www.cplusplus.com/forum/windows/140661/2/#msg744587

[28poGNh0]

I searched in google and I didnt found anything ,how did you do that?

[helios]

Yeah. I don't see anything particularly distinctive about that code.

[MiiNiPaa]

Just picked random part which is probably written specially for this code and not pasted from elsewhere and then run search on this site (I wanted to check this statement: "I probably copied it from someone's post here to test it."). So, here is the search request:

		string.resize(size, '-'); 		char_t *p = &string[0]; 		size_t length = string.size(); site:cplusplus.com/forum

https://www.google.com/search?q=%09%09string.resize%28size%2C+%27-%27%29%3B+%09%09char_t+*p+%3D+%26string[0]%3B+%09%09size_t+length+%3D+string.size%28%29%3B+site%3Acplusplus.com%2Fforum&ie=utf-8&oe=utf-8