How to use IStringStream to read from a file?

Question

I need to read in an expression from a file using a string stream and convert the expression to into another form. But I am having trouble figuring out how to read lines from the file using the Istringstream. Can anyone help me with the #includes and syntax for this? Thanks

You can't, you need a **file** stream to read from files, **string** streams are for strings. — Jesse Good, Jul 02 '12 at 01:21

score 1 · Accepted Answer · edited Jul 02 '12 at 02:00

1

#include <fstream>

std::ifstream file("filename.txt");

StuffType stuff;
while(file >> stuff)
{
    // If you are here you have successfully read stuff.
}

edited Jul 02 '12 at 02:00

Martin York

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answered Jul 02 '12 at 01:27

David

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score 1 · Answer 2 · answered Jul 02 '12 at 07:23

1

As an addition to the answer of Dave above: to read one line from a file, you can use the following code:

char buf[256];
file.getline(buf,256);

The character string buf then contains the line of text in the file.

answered Jul 02 '12 at 07:23

physicalattraction

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I tried that too, but I couldn't find the right syntax. Perhaps you can help? This does at least NOT work: std::string buf; file.getline(buf, 256); Neither does it work if you remove the second argument in getline. – physicalattraction Jul 02 '12 at 13:44
1

`getline` for `string` is not a member. The syntax is `std::getline( file, buf );` – Potatoswatter Jul 03 '12 at 01:37

How to use IStringStream to read from a file?

2 Answers2