C++ Help, File System Simulation

[Navlag]

I am getting the following error:

PII.cpp:266: error: 'struct std::string' has no member named 'getfirstblock'

And I'm not sure how to fix it, since "int block" has to be equal to the firstblock of the file, how can I fix that error?

Also, my "getfirstblock" function should return the block number of the first block in string file but I am not sure how to implement it correctly, any suggestions?

Any help is appreciated, thanks in advance

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <sstream>
#include <sstream>

using namespace std;

//Pdisk Class
class Pdisk
{
public:
    Pdisk();                //default constructor
    Pdisk(string diskname, int numberofblocks, int blocksize);
    int getblock(int blocknumber, string& buffer);
    int putblock(int blocknumber, string buffer);
    int getblocksize();
    int getnumberofblocks();
private:
    string diskname;		//file name of pseudo-disk
    int numberofblocks;		//number of blocks on disk
    int blocksize;			//block size in bytes
};
#include <cmath>
#include <vector>
#include <string>

class Filesys
{
public:
	Filesys(Pdisk& disk);
    Filesys();
	int fsclose();
	int fssynch();
	int newfile(string file);
	int removefile(string file);
	int getfirstblock(string file);
	int addblock(string file, string block);
	int delblock(string file, int blocknumber);
	int getblock(string file, int blocknumber, string& buffer);
	int putblock(string file, int blocknumber, string  buffer);
	int nextblock(string file, int blocknumber);
private:
	bool findfile( string file, int* index = NULL );
private:
	Pdisk			&disk;
	int				rootsize;
	int				fatsize;
	vector<string>  filename;
	vector<int>		firstblock;
	vector<int>		fat;
};


//Blocking
vector<string>block(string s, int b)
{
    float numberofblocks = (float)s.size( ) / b;
    
    vector<string>blocks;
    if(s.size() % b == 0)
    {
        numberofblocks = s.size()/b+1;
    }
    else
    {
        numberofblocks = s.size()/b+1;
    }
    string tempblock;
    for(int i = 0; i < numberofblocks; i++)
    {
        tempblock = s.substr(b*i,b);
        blocks.push_back(tempblock);
    }
    int lastblock = blocks.size() - 1;
    for(int i = blocks[lastblock].size(); i < b; i++)
    {
        blocks[lastblock] += "#";
    }
    return blocks;
}

// Constructor for File System
Filesys::Filesys(Pdisk& disk)
:disk(disk),
rootsize(disk.getblocksize()/10),
fatsize(4*disk.getnumberofblocks()/disk.getblocksize()),
filename(rootsize,"XXXXX"),
firstblock(rootsize,0),
fat(disk.getnumberofblocks(),0)
{
    string buffer;
    disk.getblock(2, buffer);
    if (buffer[0] == '#')
    {
        fat[0] = fatsize + 2;
        for(int i = fatsize + 2; i < disk.getnumberofblocks() - 1; ++i)
        {
            fat[i] = i + 1;
            fat[fat.size( )-1] = 0;//
        }
        //fat[fat.size( )-1] = 0;
    }
    else
    {
        string root;//was by string buffer

        disk.getblock(1,root); 
        
        istringstream rootstream(root);
        
        for(int i = 0; i < rootsize; ++i )
            rootstream >> filename[i] >> firstblock[i];
        
        string FAT;
        
        for(int i = 0; i < fatsize; ++i)
        {
            string temp;
            disk.getblock(i + 2, temp);
            FAT += temp;
        }
        
        istringstream fatstream(FAT);
        
        for(int i = 0; i < disk.getnumberofblocks( ); ++i)
            fatstream >> fat[i];
    }
    fssynch();
}

//FsSynch
int Filesys::fssynch( )
{
	// Output root directory to disk.
	ostringstream rootstream;
    
	for( int i = 0; i < rootsize; ++i )
		rootstream << filename[i] << " " << firstblock[i] << " ";
    
	string root = rootstream.str( );
    
	for( int j = root.size( ); j < disk.getblocksize( ); ++j )
		root += "#";
    
	disk.putblock( 1, root );
	
	// Output FAT to disk.
	ostringstream fatstream;
    
	for( int i = 0; i < disk.getnumberofblocks( ); ++i )
		fatstream << fat[i] << " ";
    
	string fat = fatstream.str( );
    
	for( int j = fat.size( ); j < fatsize * disk.getblocksize( ); ++j )
		fat += "#";
    
	for( int k = 0, block = 2; k < fatsize; ++k )
	{
		string temp = fat.substr( k * disk.getblocksize( ), disk.getblocksize( ) );
		disk.putblock( k + block, temp );
	}
    
	return 1;
}

//NewFile
int Filesys::newfile( string file )
{
	if( findfile( file ) )
		return 0; // File found.
    
	if( file.size( ) > 5 )
	{
		cout << "Filename '" << file << "' too large, max size is " << 5 << " chars!" << endl;
		return 0; // Filename too large.
	}
    
	for( int i = 0; i < filename.size( ); ++i )
		if( filename[i] == "XXXXX" )
		{
			filename[i]   = file;
		}
}

//RemoveFile
int Filesys::removefile(string file)
{
	int index;
	if( findfile( file, &index ) )
		if( firstblock[index] == 0 )
		{
			filename[index] = "XXXXX";
			fssynch( );
			return 1;
		}
    
	return 0; // File not empty or was not found.
}

//GetFirstBlock
int Filesys::getfirstblock(string file)
{
    /*int* index = NULL;
    return firstblock[*index];*/
    
    int index;
	if( findfile( file, &index ) )
		return firstblock[index];
    
	return 0; // File does not exist.
}

//AddBlock
int Filesys::addblock( string file, string buffer )
{
	if( fat[0] == 0 )
		return -1; // File system full.
    
	int index;
	if( !findfile( file, &index ) )
		return 0; // File not found.
    
	// Update free list.
	int ablock = fat[0];
	fat[0] = fat[ablock];
    
	// Get first block.
	int fblock = firstblock[index];
	
	// If the file is empty, update first block list.
	if( fblock == 0 ) 
	{
		firstblock[index] = ablock;
		fat[ablock] = 0;
	}
	// Search through FAT for the last block in file.
	else
	{
		while( fat[fblock] != 0 )
			fblock = fat[fblock];
        
		fat[fblock] = ablock;
		fat[ablock] = 0;
	}
    
	disk.putblock( ablock, buffer );
    
	fssynch( );
    
	return ablock;
}

//DeleteBlock
int Filesys::delblock(string file, int blocknumber)
{
    bool found = false;
    int block = file.getfirstblock();
    if (block == 0)
    {
        return 0;
    }
    if(block == blocknumber)
    {
        found = true;
        for (int i = 0; i < rootsize; i++)
        {
            if(filename[i] == file)
                firstblock[i] = fat[block];
            break;
        }
    }
    else // blocknumber is not the first block
    {
        int i = block;
        while(fat[i] != 0)
        {
            if(fat[i] != 0)
            {
                fat[i] == fat[fat[i]];
                found == true;
            }
        }
    }
    if (!found)
    {
        return 0;
    }
    fat[blocknumber] = fat[0];
    fat[0] = blocknumber;
    fssynch();
}

//GetBlock
int Filesys::getblock( string file, int blocknumber, string& buffer )
{
	disk.getblock( blocknumber, buffer );
    
	return 1;
}

//PutBlock
int Filesys::putblock( string file, int blocknumber, string buffer )
{
	disk.putblock( blocknumber, buffer );
    
	return 1;
}

//NextBlock
int Filesys::nextblock( string file, int blocknumber )
{
    //return -1; // Block does not belong to file.
    
    return fat[blocknumber];
    
	//return -1; // File not found.
}

//FindFile
bool Filesys::findfile( string file, int* index )
{
	for( int i = 0; i < filename.size( ); ++i )
		if( filename[i] == file )
		{
			if( index ) *index = i;
			return true;
		}
    
	return false;
}

//Pdisk - Default Constructor
Pdisk::Pdisk()
{
    
}

//Pdisk
Pdisk::Pdisk(string disk_name, int number_of_blocks, int block_size)
{  
    diskname = disk_name; 
    numberofblocks = number_of_blocks;
    blocksize = block_size;
    fstream output(diskname.c_str(),ios::out); 
    int i, j;
    for(i = 1; i <= numberofblocks; i++)
    {
        for(j = 1; j <= blocksize; j++)
        {
            output << "#";
        }
    } 
    output.close();
}

//GetBlock
int Pdisk::getblock(int blocknumber, string& buffer)
{
    fstream input;
    input.open (diskname.c_str(), ios::in);
    if (input.bad())
    {
        return 0;
    }
    if (input.is_open())
    {
        input.seekg(blocknumber * blocksize + 1, ios::beg);
        char x;
        for(int i = 0; i < blocksize; i++)
        {
            x = input.get();
            buffer = buffer + x;
        }
        input.close();
        return 1;
    }
}

//PutBlock
int Pdisk::putblock(int blocknumber, string buffer)
{
    fstream output;
    output.open(diskname.c_str(),ios::in | ios :: out);
    if(output.bad())
    {
        return 0;
    }
    output.seekp(blocknumber * blocksize + 1, ios::beg);
    char x;
    for(int i = 0; i < buffer.length(); i++)
    {
        x = buffer[i];
        output.put(x);
    }
    output.close();
    return 1;
}

//GetBlockSize
int Pdisk::getblocksize()
{
    return blocksize;
}

//GetNumberOfBlocks
int Pdisk::getnumberofblocks()
{
    return numberofblocks;
}

//Drivers
int main()
{
    Pdisk disk1("test.txt",128,128);
    Filesys fsys(disk1);
    fsys.delblock("XXXXX", 6);
}

[baldwindc]

Here is what you are doing wrong:

Say that you have

stirng s;

and you want to get the length

cout << s.length();

or you want to insert a character

s.insert('x');

or invoke any of the function associated with the string object.

Okay, thats fine. But a string is just that, an object. It has predefined methods associated with it. Unfortunately, at least to the best of my knowledge, you can not make up a new method for a predefined object.

However, you can pass it to a function and do the calculations there

int getBlockSize(string *s) ; 
// and in main
myReturnValue = getBlockSize(&s)