string conversion

[scottincz]

Hi gang

I have a file that contains floating point numbers in text like this
-0.321435435D-02
0.4324325435D-02
1.4343243434D+00
2.4343434343D+5
-0.432432443D+2
etc
etc

i need to be able to loop through the file and convert each line ot a double where d-xx is the . placement
for example
0.4324325435D-02 = 0.004324325435
and
-0.432432443D+2 = -043.2432443

any tips on achieving this.
Thanks in advance
Scott

[Alexey B]

Originally posted by MSDN:

double atof( const char *string );

The string argument to atof has the following form:
[whitespace] [sign] [digits] [.digits] [ {d | D | e | E }[sign]digits]

That should help you.

[Philip Nicoletti]

standard C++ i/o should take care of this.
(following code not tested ...)

#include <fstream>
#include <iostream>

using namespace std;

int main()
{
	ifstream in("input.txt");

	if (!in)
	{
		cout << "could not open file" << endl;
		return 1;
	}

	double d;
	while (in >> d && !in.fail())
	{
		cout << "read from file : " << d << endl;
	}

	return 0;
}

[scottincz]

You missed the point. I can read each line of text from the file but i need to convert the string format of a double (non standard) to a double.
thanks
Scott

[Alexey B]

The atof function does just that. The format of your string corresponds to the format that the function accepts, so using it should be an easy task. Check MSDN for more information on atof.

[Meijian An]

...

char ss[256];

while(...)
{

//read double d from your file.

sprintf(ss,"%f",d);
cout<<<ss<<endl;

//or use cout.width(..) and cout.setf(..)

...
}

[cup]

Are you just mixing up external and internal representations of the same number? If you read 0.4324325435D-02 and printf it in f format, you will get 0.004324325435. If you printf it in E format, you will get 0.4324325435E-02. Those are just external fomats. Internally, the number is the same.

[jfaust]

I think you're confused where I was confused.

0.4324325435D-02 is a legal format for a double value.

Jeff

[Paul McKenzie]

Originally posted by scottincz
You missed the point. I can read each line of text from the file but i need to convert the string format of a double (non standard) to a double.
thanks
Scott

There is another standard function besides atof() and that is strtod(). Either one should work for you.

Regards,

Paul McKenzie