Thread: memory mapping

Don't type anything. Type the name of the program, then take your hands off the keyboard. Sneak one finger back on to press the enter key, but resist the urge to type a bunch of things before pressing enter.

Ok thanks I tried that but it does try to open but then crashes

Well, I suppose:

Code:

cout << "opening for read: " << argv[1] << endl;

If you don't provide arguments, argv[1] doesn't exist.

so I would just replace all argv with inFilename and outFilename?

OK I got my input file to work and it now I do a copy con input.txt and it loads into my input file successfully....

Now when I open my output file it is not doing as it should...I also checked the requirements and I do need argc and argv...can anyone see why my output file is blank as it should be storing palindromes?

Code:

#include <windows.h>
#include <iostream>
#include <string>
#include <algorithm>
#include <list>
using namespace std;

bool isPalindrome(const std::string& s)
{
    return s == string(s.rbegin(),s.rend());
}

//MAIN FUNCTION

int main(int argc, char *argv[])
{

    HANDLE readFile, writeFile;
    HANDLE readFileMap, writeFileMap;
    PVOID pvreadFile, pvwriteFile;
    DWORD readFileSize;
    string word = "";
    list<string> words;

	//Test file
	//char inFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome\\Input.txt";
	char inFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome\\Input.txt";

    //VERIFYING ARGUMENTS
    if(argc = 2 )
    {
        cout << "opening for read: " << argv[1] << endl;
        readFile = CreateFile(inFilename, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

        //IF STATEMENT TO CHECK IF THE READ FILE IS NOT VALID
        if(readFile == INVALID_HANDLE_VALUE)
        {
            //DISPLAY ERROR MESSAGE
            cout << "Read file could not be opened. Error code: " << GetLastError() << endl;
            return(FALSE);
        }

        readFileMap = CreateFileMapping(readFile, NULL, PAGE_READONLY, 0, 0, NULL);

        //IF STATEMENT TO SEE IF THE READFILEMAP IS NULL
        if(readFileMap == NULL)
        {
            //DISPLAY ERROR MESSAGE
            cout << "Read file map could not be opened. Error code: " << GetLastError() << endl;
            CloseHandle(readFile);
            return(FALSE);
        }

        pvreadFile = MapViewOfFile(readFileMap, FILE_MAP_READ, 0, 0, 0);

        //IF STATEMENT TO DETERMINE IF PVREADFILE IS NULL
        if(pvreadFile == NULL)
        {
            //DISPLAY ERROR MESSAGE
            cout << "Could not map view of read file. Error code: " << GetLastError() << endl;
            CloseHandle(readFileMap);
            CloseHandle(readFile);
            return(FALSE);
        }

        //DETERMINE SIZE LIMIT OF INPUT FILE
        readFileSize = GetFileSize(readFile, NULL);

        cout << "Opening for write: " << argv[2] << endl;
        //writeFile = CreateFile(argv[2], GENERIC_READ | GENERIC_WRITE, 0, NULL, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, NULL);

		//test file
		char outFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome";
		//char outFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome\\Output.txt";

        writeFile = CreateFile(outFilename, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

        //IF STATEMENT TO DETERMINE IF WRITE FILE IS VALID OR NOT
        if(writeFile == INVALID_HANDLE_VALUE)
        {
            //DISPLAY ERROR MESSSAGE IF FILE CAN'T BE OPENED
            cout << "Write file could not be opened. Error code: " << GetLastError() << endl;
            //cout << "argv[1] = " << argv[1] << " argv[2] = " << argv[2] << endl;
            UnmapViewOfFile(pvreadFile);
            CloseHandle(readFileMap);
            CloseHandle(readFile);
            return(FALSE);
        }

        writeFileMap = CreateFileMapping(writeFile, NULL, PAGE_READWRITE, 0, readFileSize, NULL);

        //IF STATEMENT TO DETERMINE IF WRITE FILE MAP IS NULL
        if(writeFileMap == NULL)
        {
            //DISPLAY ERROR MESSAGE THAT THE WRITE FILE CANNOT BE MAPPED
            cout << "Write File could not be mapped. Error code: " << GetLastError() << endl;
            CloseHandle(writeFile);
            UnmapViewOfFile(pvreadFile);
            CloseHandle(readFileMap);
            CloseHandle(readFile);
            return(FALSE);
        }

        pvwriteFile = MapViewOfFile(writeFileMap, FILE_MAP_WRITE, 0,0,0);

        //IF STATEMENT IF THE PVWRITEFILE IS NULL
        if(pvwriteFile == NULL)
        {
            //DISPLAY ERROR MESSAGE THAT I COULD NOT OPEN MAP VIEW OF WRITE FILE
            cout << "Could not open map view of write file. Error code: " << GetLastError() << endl;
        }

        //CLEANUP THE FILE
        UnmapViewOfFile(pvwriteFile);
        UnmapViewOfFile(pvreadFile);
        CloseHandle(writeFileMap);
        CloseHandle(readFileMap);
        CloseHandle(writeFile);
        CloseHandle(readFile);

    }
    //ELSE STATEMENT IF CANNOT FIND FILE
    else
    {
        //DISPLAY ERROR MESSAGE THAT NO FILE IS Given
        switch( argc )
        {
            case 0:
                cout << "No arguments given" << endl;
                break;
            case 1:
                cout << "No read file or write file given" << endl;
                break;
            case 2:
                cout << "No write file given" << endl;
                break;
            default:
                cout << "too many arguments given." << endl;
        }
    }

    //cout << "Arg 0 = file to read" << endl;
    //cout << "Arg 1 = file to write to" << endl;

    //RETURN A VALUE
    return 0;
}

Do you ever even attempt to write something to your output file?

This is what I did for any letter in the input file I want to cout to the output file. I am sure it is something very simple on what I am doing wrong

Code:

#include <windows.h>
#include <iostream>
#include <string>
#include <algorithm>
#include <list>
using namespace std;

bool isPalindrome(const std::string& s)
{
    return s == string(s.rbegin(),s.rend());
}

//MAIN FUNCTION

int main(int argc, char *argv[])
{

    HANDLE readFile, writeFile;
    HANDLE readFileMap, writeFileMap;
    PVOID pvreadFile, pvwriteFile;
    DWORD readFileSize;
    string word = "";
    list<string> words;

	//Test file
	//char inFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome\\Input.txt";
	char inFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome\\Input.txt";

    //VERIFYING ARGUMENTS
    if(argc == 2 )
    {
        cout << "opening for read: " << argv[1] << endl;

        readFile = CreateFile(inFilename, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

		//declare string variable
		string txt;
		for (int j=0; j<int(txt.size()); ++j)	
		{
			 (txt[j]=='a' || txt[j]=='b' || txt[j]=='c' || txt[j]=='d' || txt[j]=='e' || txt[j]=='f'
				|| txt[j]=='g' || txt[j]=='h' || txt[j]=='i' || txt[j]=='j' || txt[j]=='k' || txt[j]=='l'
				|| txt[j]=='m' || txt[j]=='n' || txt[j]=='o' || txt[j]=='p' || txt[j]=='q' || txt[j]=='r'
				|| txt[j]=='s' || txt[j]=='t' || txt[j]=='u' || txt[j]=='v' || txt[j]=='w' || txt[j]=='x' 
				|| txt[j]=='y' || txt[j]=='z');
		}

        //IF STATEMENT TO CHECK IF THE READ FILE IS NOT VALID
        if(readFile == INVALID_HANDLE_VALUE)
        {
            //DISPLAY ERROR MESSAGE
            cout << "Read file could not be opened. Error code: " << GetLastError() << endl;
            return(FALSE);
        }

        readFileMap = CreateFileMapping(readFile, NULL, PAGE_READONLY, 0, 0, NULL);

        //IF STATEMENT TO SEE IF THE READFILEMAP IS NULL
        if(readFileMap == NULL)
        {
            //DISPLAY ERROR MESSAGE
            cout << "Read file map could not be opened. Error code: " << GetLastError() << endl;
            CloseHandle(readFile);
            return(FALSE);
        }

        pvreadFile = MapViewOfFile(readFileMap, FILE_MAP_READ, 0, 0, 0);

        //IF STATEMENT TO DETERMINE IF PVREADFILE IS NULL
        if(pvreadFile == NULL)
        {
            //DISPLAY ERROR MESSAGE
            cout << "Could not map view of read file. Error code: " << GetLastError() << endl;
            CloseHandle(readFileMap);
            CloseHandle(readFile);
            return(FALSE);
        }

        //DETERMINE SIZE LIMIT OF INPUT FILE
        readFileSize = GetFileSize(readFile, NULL);

        cout << "Opening for write: " << argv[2] << endl;
        //writeFile = CreateFile(argv[2], GENERIC_READ | GENERIC_WRITE, 0, NULL, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, NULL);

		//test file
		char outFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome";
		//char outFilename[] = "C:\\Users\\Bryan\\Documents\\CSI 345\\Palindrome\\Palindrome\\Output.txt";

        writeFile = CreateFile(outFilename, GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
		
		
		
		//show output
		//cout<<txt[j];
		cout << txt;

        //IF STATEMENT TO DETERMINE IF WRITE FILE IS VALID OR NOT
        if(writeFile == INVALID_HANDLE_VALUE)
        {
            //DISPLAY ERROR MESSSAGE IF FILE CAN'T BE OPENED
            cout << "Write file could not be opened. Error code: " << GetLastError() << endl;
            //cout << "argv[1] = " << argv[1] << " argv[2] = " << argv[2] << endl;
            UnmapViewOfFile(pvreadFile);
            CloseHandle(readFileMap);
            CloseHandle(readFile);
            return(FALSE);
        }

        writeFileMap = CreateFileMapping(writeFile, NULL, PAGE_READWRITE, 0, readFileSize, NULL);

        //IF STATEMENT TO DETERMINE IF WRITE FILE MAP IS NULL
        if(writeFileMap == NULL)
        {
            //DISPLAY ERROR MESSAGE THAT THE WRITE FILE CANNOT BE MAPPED
            cout << "Write File could not be mapped. Error code: " << GetLastError() << endl;
            CloseHandle(writeFile);
            UnmapViewOfFile(pvreadFile);
            CloseHandle(readFileMap);
            CloseHandle(readFile);
            return(FALSE);
        }

        pvwriteFile = MapViewOfFile(writeFileMap, FILE_MAP_WRITE, 0,0,0);

        //IF STATEMENT IF THE PVWRITEFILE IS NULL
        if(pvwriteFile == NULL)
        {
            //DISPLAY ERROR MESSAGE THAT I COULD NOT OPEN MAP VIEW OF WRITE FILE
            cout << "Could not open map view of write file. Error code: " << GetLastError() << endl;
        }

        //CLEANUP THE FILE
        UnmapViewOfFile(pvwriteFile);
        UnmapViewOfFile(pvreadFile);
        CloseHandle(writeFileMap);
        CloseHandle(readFileMap);
        CloseHandle(writeFile);
        CloseHandle(readFile);

    }
    //ELSE STATEMENT IF CANNOT FIND FILE
    else
    {
        //DISPLAY ERROR MESSAGE THAT NO FILE IS Given
        switch( argc )
        {
            case 0:
                cout << "No arguments given" << endl;
                break;
            case 1:
                cout << "No read file or write file given" << endl;
                break;
            case 2:
                cout << "No write file given" << endl;
                break;
            default:
                cout << "too many arguments given." << endl;
        }
    }

    //cout << "Arg 0 = file to read" << endl;
    //cout << "Arg 1 = file to write to" << endl;

    //RETURN A VALUE
    return 0;
}

sorry man i am just trying to figure out why this is doing what it is doin and lost

It is not doing anything, because you have literally not written a useful line of code anywhere in this program. You open two files. You close them. That is all. You never attempt to read from the files, you never attempt to process the input in any way, nor do you make any attempt at writing to a file. Your program is not sentient, and will not just decide to do things all on its own. You need to decide what you want to have the program do, and then make it do that.

Originally Posted by tabstop

It is not doing anything, because you have literally not written a useful line of code anywhere in this program.

I think he should just go to his teacher and say I can't do it. Looking at Google he's had this assignment for at least three months and the code is hardly any further along to its goal now than it was then, and that includes 3 forums worth of people essentially writing it for him. I don't know where it is, but somewhere there's got to be a line between continued perseverance and just plain time wasting.