easy C programming question

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I made a program thats reads X and Y values from a

ascii file,converts the values from english to metric,

and writes the data to another file.

I use fscanf(fp,"%f",&X) and fprintf(fp,"%.3lf",X) for this. If X = 1.71, result will be X43.434..good

If X = .03937 result will be X1.000. How do I

eliminate the trailing zero's before output so my answer will be X0. Thanks,

Dave