A search and replace function for use with other C++ programs.

searchreplace.cpp

//
// Compile with:
// $ g++ -O3 -Wall searchreplace.cpp -o searchreplace
//
// Run with:
// $ searchAndReplace
//
//
// This program searches for user specified text strings (a starting point
// point to an ending point) and replaces them and all contents between
// with text new text.
//
// Example:
//
// Text:	"Some great words cannot defeat a great program!"
// Begin:	"cannot"
// End:		"great"
// Replace:	"in a decent"
// Result:	"Some great words in a decent program!"
//
// Regex equivalent: /cannot[^great]*great/
//
// If the user enters the beginning searched text as "", then the program
// replaces from the beginning of the string to the first instance of text;
// likewise, if the user enters "" for the end point, the text will be
// replaced from the first instance of the starting word, to the end. The
// user may change this functionality to have just the one word itself be
// replaced by un/commenting the appropriate code.
//
// Due to input/output checking, this program should never run into an
// infinit loop. The bool return lets other functions know if the text was
// or could have been changed.
//

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

using namespace std;


bool findAndReplaceAllBetween(string &trueText, const std::string &strBegin, const std::string &strEnd, const std::string &strReplace)
{

	std::size_t beginFound;
	std::size_t endFound;

	if (strEnd.empty())
	{
		if (strBegin.empty())
		{
			trueText = strReplace;
			return true;		// Shows that a change has or could be made
		}

		// Option #1: Replace just the one word
		do {
			beginFound = trueText.find(strBegin);

		        // Check for the first part
			if (beginFound != std::string::npos)
			{
				// #1 - Replace just the one word (strBegin):
				if (trueText == (trueText.replace(beginFound, strBegin.length(), strReplace)))
					continue;
				else
                	      		return true;		// Don't break, it's slower. Just return straight away!
			}

			return false;

		} while (true);

		// Option #2: Replace from strBegin to end of text
		//trueText.replace(beginFound, trueText.length() - beginFound, strReplace);
		//return false;

	} else if (strBegin.empty()) {

		endFound = trueText.find(strEnd);

		if (endFound != std::string::npos)
	        {
			trueText.replace (0, endFound + strEnd.length(), strReplace);
			return true;
		}
        }


	do {
		beginFound = trueText.find(strBegin);

	        // Check for the first part
		if (beginFound != std::string::npos)
		{
			endFound = trueText.substr(beginFound + strBegin.length()).find(strEnd);

	                // Can we find the second part?
        	        if (endFound != std::string::npos)
			{
				if (trueText == trueText.replace(beginFound, strEnd.length() + endFound + strBegin.length(), strReplace))
					continue;
				else
					return true;
			}
		}

		// If we made it here, nothing was found.
		return false;

	} while(true);

	// If you made it here, something went seriously wrong; the 'return false' just above should alway catch first.
	return false;
}


int main ()
{

	const std::string  sText	= "Some great words cannot defeat a great program!";
	const std::string  sBegin	= "";
	const std::string  sEnd		= "words";
	const std::string  sReplace	= "gestures.";

	std::cout << "\n" << "Phrase:\n\n" << sText << "\n\nFrom   \"" << sBegin << "\"\nTo     \"" << sEnd << "\"\nWith   \"" << sReplace << "\"\n\n\n";
        std::string  sTextCopy;

	// Let the benchmark be the judge.
	std::clock_t start;
	double duration;
        start = std::clock();

	// What? You don't replace text this much? Fiddlesticks!
	for (int i = 0; i < 1000; i++)
	{

		// Refresh modified text with fresh new copy each time
		sTextCopy = sText;

		findAndReplaceAllBetween(sTextCopy, sBegin, sEnd, sReplace);

	}

	// 18.42

	// It's done! Stop timer!
        duration = ( std::clock() - start ) / (double) CLOCKS_PER_SEC;
	std::cout << "Duration: " << duration << "s\n\n";

	// Display text result so we know it was done and done correctly
	std::cout << sTextCopy << "\n\n\n";

	return 0;
}