ifstream

Jan 22, 2011 at 7:29pm
Hello.
I was wondering if i can choose from a text file with numbers inside the number i want exactly. For example the numbers are in 5 lines.:
5
3
6
2
7

Can i choose what to show? I want to show up only the number 2 or 7 or 3!
Is there any way to do that????
Jan 22, 2011 at 7:35pm
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int i = 0;
while (fin >> variable[i]) {
    if(variable[i] == 2 || variable[i] == 3 || variable[i] == 7)
        cout << variable[i];
    i++;
}


assuming i understand your question correctly, that will print out 2, 3 and 7 each time it reads it in from the file
Last edited on Jan 22, 2011 at 7:36pm
Jan 22, 2011 at 7:43pm
These numbers was an example.
the txt file may have 50 numbers or 100 or 10
these numbers i take them with a loop.
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 ifstream f;
f.open("data.txt");
if(f.is_open());
{
  f>>a;
 
for(int i=0; i<a; i++)
{f>>g;}

and i didnt explained that the first number will be the nuber of the lines.
5
2
5
6
3
4
. and i want to choose one number of them.

Last edited on Jan 22, 2011 at 7:47pm
Jan 22, 2011 at 7:45pm
is there any way to do this??

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int g[];
 ifstream f;
f.open("data.txt");
if(f.is_open());
{
  f>>a;
 
for(int i=0; i<a; i++)
{f>>g[];}
cout<<g[i];
Jan 22, 2011 at 7:52pm
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int g[]; //you need to give this array an explicit size
 ifstream f;
f.open("data.txt");
if(f.is_open());
{
  f>>a;
 //no closing brace for this if statement
for(int i=0; i<a; i++)
{f>>g[];} //you need to index that array
cout<<g[i]; // this is outside the for loop. i is local to the for loop, so this won't compile.


if you are looking for one specific number and you want to print it out when you find it, just put an if statement inside the for loop that will print g[i] when g[i] == the number you want
Last edited on Jan 22, 2011 at 7:53pm
Jan 22, 2011 at 7:58pm
All i want is to do a bubble sort in this txt file.
And i dont now how exactly.And i think this way will help me.If i find how to do that i will continue i think.And i searched the forum for the bubble sort but i didnt find some good tutorials with fstream.
Jan 22, 2011 at 8:01pm
it doesn't matter whether you're reading from a file or not. just read the contents of the file into your array and run the array through a bubble sort.
Jan 22, 2011 at 8:25pm
And how can i do that???
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