plz help reg FILE I/O in c++?

Question

#include

void read(ifstream &T) //pass the file stream to the function
{

char ch;

while(!T.eof())
{
T.get(ch);
cout << ch;
}

cout << endl << "--------" << endl;
}

void main()
{
ifstream T("file1.txt");
read(T);
T.close();

T.open("file2.txt");
read(T);
T.close();
}
HERE FILE1 And FILE2 ARE TWO TXET FILES.FILE 1 IS GETTING OPENED BUT FILE2 IS NOT.
WATS THE PROBLEM??

Answer 1

try this for an example, you will have to modify the code, I won't do your homework for you, but this should help you out


#include
#include

using namespace std;

bool Load(ifstream&);
bool ReadData(ifstream&, char[],int&);
void PrintData(const char[],int);
void clear(ifstream&);


void sort(char[],int);
void swapValues(char&,char&);
int indexOfSmallest(const char a[], int startIndex, int numberUsed);


int main()
{
ifstream file;
int iSize;
char cData[100];

try
{
if(!Load(file))
throw "File Handle could not be acquired";

for(int i=0; i< 3; i++)
{
if(!ReadData(file,cData,iSize))
throw "Data could not be read";
cout << iSize << endl;
PrintData(cData,iSize);
sort(cData,iSize);
PrintData(cData,iSize);
}

file.close();
}
catch(char* szError)
{
cout << endl << "Error: " << szError << endl;
exit(0x01);
}

return 0;
}

bool Load(ifstream& iFS)
{
try
{
iFS.open("c:\test.txt",ios::in);
if(!iFS.is_open())
throw false;
throw true;
}
catch(bool bCode)
{
return bCode;
}
}

bool ReadData(ifstream& iFS,char cData[], int& iSize)
{
try
{
iFS >> iSize;
if(iSize < 0);
else
{
clear(iFS);
for(int i=0;i < iSize;i++)
iFS.get(cData[i]);
clear(iFS);
}
throw true;
}
catch(bool bCode)
{
return bCode;
}
}

void clear(ifstream& iFS)
{
char c = '\0';
while(c!= '\n' && !iFS.eof())
iFS.get(c);
c='\0';
}


void PrintData(const char cData[], int iSize)
{
for(int i=0; i < iSize; i++)
cout << cData[i];
cout << endl;
}


void sort(char a[], int numberUsed)
{
int indexOfNextSmallest;
int index;

for (index = 0; index < numberUsed - 1; index++)
{
indexOfNextSmallest = indexOfSmallest(a, index, numberUsed);
swapValues(a[index], a[indexOfNextSmallest]);
}
}

void swapValues(char& v1, char& v2)
{
char temp;
temp = v1;
v1 = v2;
v2 = temp;
}

int indexOfSmallest(const char a[], int startIndex, int numberUsed)
{
int min = a[startIndex],
indexOfMin = startIndex;
int index;

for (index = startIndex + 1; index < numberUsed; index++)
if (a[index] < min)
{
min = a[index];
indexOfMin = index;
}

return indexOfMin;
}

Answer 2

I just spent a while messing round with this and it took me a bit of time, but i figured out what's gone wrong. As far as I can tell the "close" method, doesn't completely reset the ifstream class, so when you open a new file with the same ifstream instance, it still has its "eof" bit set. You can fix it, by adding:

T.clear();

After your first call to:

T.close();

At least, that fixes it on my version (C++.Net 2003)

Answer 3

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Answer 4

check if file2.txt exists OR
check permissions also OR
take different variable of ifstream OR

Answer 5

Hey read it here

http://www.chris.spear.net/pli/fileio.htm