[.Dare Devil.]

Btw my mind wasn't in normal state when i wrote my post and read your code.
It was making sense but there were some bugs in it. ( you fixed the one already. )

Anyways ... i created this but i quickly gave up since there was no way
to resize the file
even tho:
https://msdn.microsoft.com/en-us/lib...=vs.85%29.aspx
http://linux.die.net/man/2/truncate
And i got stuck on bug ( while what is smaller than with )
So i found that it wasn't worth of my time.
Anyways, here's my code:

#include <amxmodx>

public plugin_init()
{
	if( file_exists( "addons/logs.txt" ) ) delete_file("addons/logs.txt")
	replaceinfile( "addons/test.txt", "unab1234567asb", "3" )
}

#define _rif_block_size 32
stock replaceinfile( const filename[], const what[], const with[] )
{
	new f = fopen( filename, "rb" );
	new whatsize = strlen( what );
	new withsize = strlen( with );
	new blocksize = _rif_block_size - 1;
	new readsize[2] = {0,0};
	new mypos = 0;
	new foundin = -1;
	new myblock[2][_rif_block_size * 2];
	new b = 0;
	while((readsize[b] = fread_blocks( f, myblock[b], blocksize, BLOCK_CHAR )))
	{
		zs_log( "b:%d,%d", b, readsize[b]  )
		myblock[b][readsize[b] + 1] = 0;
		if( mypos )
		{
			add(myblock[b], readsize[b], myblock[(!b)]);
			myblock[(!b)][0] = 0;
			zs_log( "check:%s from:%s", what, myblock[b] )
			foundin = contain(myblock[b], what);
		} 
		else foundin = contain(myblock[b], what);
		
		if( foundin != -1 )
		{
			mypos += foundin;
			fclose(f);
			f = fopen( filename, "r+b" );
			fseek(f, 0, SEEK_END);
			new fsize = ftell(f);
			new current = fsize;
			new stepsize;
			readsize[0] = _rif_block_size - 1;
			if( withsize > whatsize )
			{
				mypos += whatsize;
				stepsize = withsize - whatsize;
				while( current > mypos )
				{
					if( mypos > current - readsize[0] ) readsize[0] = current - mypos;
					current -= readsize[0];
					fseek(f, current, SEEK_SET);
					fread_blocks( f, myblock[0], readsize[0], BLOCK_CHAR );
					fseek(f, current + stepsize, SEEK_SET);
					fwrite_blocks(f, myblock[0], readsize[0], BLOCK_CHAR );
				}
				fseek(f, mypos - whatsize, SEEK_SET);
				fwrite_blocks(f, with, withsize, BLOCK_CHAR );
				break;
			}
			stepsize = whatsize - withsize;
			current = mypos + whatsize;
			new pr = fsize - stepsize - 1;
			while( current < pr )
			{
				zs_log( "distance:%d/%d pr:%d", pr - current, current, pr )
				if( current + readsize[0] > pr) readsize[0] = pr - current;
				zs_log(  "writesize:%d", readsize[0])
				fseek(f, current, SEEK_SET);
				fread_blocks( f, myblock[0], readsize[0], BLOCK_CHAR );
				fseek(f, current - stepsize, SEEK_SET);
				fwrite_blocks(f, myblock[0], readsize[0], BLOCK_CHAR );
				current += readsize[0];
			}
			
			fseek(f, mypos, SEEK_SET);
			fwrite_blocks(f, with, withsize, BLOCK_CHAR );
			
			
			for( new b = 0; b <= stepsize; b++ ) myblock[0][b] = 0;
			fseek(f, fsize - stepsize, SEEK_SET);
			fwrite_blocks(f, myblock[0], stepsize, BLOCK_CHAR );
			break;
		}
		zs_log( "here" );
		b = (!b);
		myblock[b][0] = 0;
		mypos += readsize[0];
	}
	fclose(f);
}

public zs_log( in[], any:... )
{
	static a[1024]
	vformat(a, charsmax(a), in, 2)
	write_file( "addons/logs.txt", a, -1)
}

oh btw @Bugsy
that what you didn't had patience to understand.
Half of it didn't make any sense. It made sense but a bad sense i guess.

I'm not going to say what, where, i took or did but by that reason, my ability to think deep was terrible.

Sowwy about everything xD

[Bugsy]

Here's a line by line flavor

PHP Code:

ReplaceTextInFile( const szFile[] , const szFind[] , const szReplaceWith[] )
{
    new iSrcFile , iDestFile , szDestFile[ 64 ] , szLine[ 255 ];
    
    formatex( szDestFile , charsmax( szDestFile ) , "%s_tmp" , szFile );
    
    if ( ( iSrcFile = fopen( szFile , "r" ) ) && ( iDestFile = fopen( szDestFile , "w+" ) ) )
    {
        while ( fgets( iSrcFile , szLine , charsmax( szLine ) ) )
        {
            replace_all( szLine , charsmax( szLine ) , szFind , szReplaceWith );
            fputs( iDestFile , szLine );
        }
        
        fclose( iSrcFile );
        fclose( iDestFile );
    }
    
    return ( iSrcFile && iDestFile && delete_file( szFile ) && rename_file( szDestFile , szFile , 1 ) );
}