CODEWITHSUNDEEP
c++file-io
Subbu
Subbu

Reputation: 2101

second call of seekg not working

In my following code , I am counting the number of words , lines and then calculating the size of text file . The first use of seekg works fine after the first while loop but after the second while loop , it doesn't work . it gives values as shown in output .

#include <iostream>
#include <fstream>
using namespace std ;

int main(void)
{
    fstream  txtFile;
    txtFile.open("test.txt");

    if(txtFile.is_open())
    {
        printf("txt file is opened");
    }

    //number of words and lines in txt file
    int w=0 , l =0 ;
    int c , start , end;
    string s;

    while(1)
    {
        if(txtFile.peek() == -1)
            break;
        c = txtFile.get();
        if(c != txtFile.eof())
                    w++;
    }

    txtFile.seekg(0,ios::beg);

    while(getline(txtFile,s))
    {
         l++ ;
    }
    printf("no of words : %d , no of  lines: %d\n",w,l);

    //calculate the size of both the files
    txtFile.seekg(0,ios::beg);
    start = txtFile.tellg();
    printf("%d\n",start);;
    txtFile.seekg(0, ios::end);
    end = txtFile.tellg();
    printf("%d\n",end);;

    return 0 ;
}


OUTPUT
txt file is opened
no of words : 128 , no of  lines: 50
-1
-1

Upvotes: 1

Views: 1501

Answers (1)

Captain Obvlious
Captain Obvlious

Reputation: 20083

The last input operation causes the fail bit to be set. If you call tellg while this bit is set it too will fail. You need to call clear() before you call tellg().

txtFile.clear(); // clear fail bits
txtFile.seekg(0,ios::beg);

Upvotes: 6

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