C字符串压缩算法

#include <iostream>
#include <stdlib.h>
//#include <algorithm>

using namespace std;

void stringZip( const char* pInputStr, long lInputLen, char* pOutputStr )
{
	if( !pInputStr || lInputLen <= 1 || !pOutputStr )
		return;
	memset( pOutputStr, 0, lInputLen );

	char cValue = *pInputStr;//重复字母对比值
	long lCount = 0;//单一字符重复字母个数
	int iIndex = 0;//pInputStr迭代位置
	int iCur = 0;//pOutputStr当前指针偏移
	int iNumLen = 0;//压缩字母的个数长度
	char buf[16];//字母长度缓存

	while( lInputLen-- )
	{
		if( cValue == *( pInputStr + iIndex++ ) )
		{//遇到重复字符
			lCount++;//
		}
		else
		{
			if( lCount > 1 )
			{//重复字符
				memset( buf, 0, 16 );
				itoa( lCount, buf, 10 );
				strcat( pOutputStr, buf );
				iNumLen = strlen( buf );
			}

			iCur += iNumLen;
			*( pOutputStr + iCur ) = cValue;//append字符
			iCur++;
			
			cValue = *(pInputStr + iIndex - 1);//取下一个待比较的字符
			

			//重新计算位置
			iIndex--;
			lInputLen++;

			//重置计数器
			iNumLen = 0;
			lCount = 0;
		}
	}
}

char* stringUnzip( const char* pStrIn )
{//
	if( !pStrIn || !strlen(  pStrIn ) )
		return NULL;

	long lLen = strlen( pStrIn );
	const int INCREMENT = 1024;

	//先将结果字符串设置为输入字符串的5倍大小
	long lCurNums = 5  *  lLen * sizeof( char );
	char* pStrOut = (char*)malloc( lCurNums );

	if( !pStrOut )
		return NULL;

	memset( pStrOut, 0, lCurNums );

	long lNum = 0;//重复字母个数
	int iNumLen = 0;//重复字母长度
	int iCur = 0;//结果集当前指针偏移
	char numBuf[16];//用于计算数字长度
	char cValue;	//临时字符值
	const long constLen = lLen;
	long lIndex = constLen - lLen;//pStrIn的字符串偏移值

	int i;
	while( lIndex < constLen )
	{
		lIndex = constLen - lLen;//

		lNum = atoi( ( pStrIn + lIndex ));//字符个数

		if( lNum > 0 )
		{//字符个大于1
			if( iCur + lNum >= lCurNums -1 )
			{//空间不足
				lCurNums += INCREMENT;

				pStrOut = (char*)realloc( pStrOut, lCurNums );
				
				if( !pStrOut )
					return NULL;
			}

			memset( numBuf, 0, 16 );
			itoa( lNum, numBuf, 10 );
			
			iNumLen = strlen( numBuf );//取数字长度
			cValue = *( pStrIn + lIndex + iNumLen );//取压缩的字符

			for( i = 0; i < lNum; i++ )//还原压缩的字符
			{
				*( pStrOut + iCur++ ) = cValue;
			}


		}
		else
		{//未压缩的单一字符
			if( iCur >= lCurNums -1 )
			{//空间不足
				lCurNums += INCREMENT;

				pStrOut = (char*)realloc( pStrOut, lCurNums );

				if( !pStrOut )
					return NULL;
			}

			*(pStrOut + iCur++ ) = *( pStrIn + lIndex + iNumLen );
		}

		lLen = lLen - iNumLen - 1;//计算偏移值
		iNumLen = 0;

	}

	return pStrOut;

}

int main( int argc, char* argv[] )
{
	char* pInStr = "aaaabasdfaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa" 
		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"
		"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaccccddddeeeadfaadfa";
	int iLen = strlen( pInStr ) + 1;

	char* pOutStr = (char*)malloc( iLen );
	memset( pOutStr, 0, iLen );

	//压缩字符
	stringZip( pInStr, iLen, pOutStr );
	puts( pOutStr );

	//还原压缩的字符
	char* pUnzipStr = stringUnzip( pOutStr );
	puts( pUnzipStr );

 　　　free( pUnzipStr );
	pUnzipStr = NULL;

	return 0;
}