Re: [Haskell-cafe] FFI to double constants, printf

You probably want something like printf("%.10Lg",d);. Here's a shot C example and its output: #include int main(int argc, char * argv[]) { long double d = 0.123456789; printf("%.30Lf\n", d); printf("%.20Lg\n", d); printf("%.20Le\n", d); } /* 0.123456788999999997336054491370 0.12345678899999999734 1.23456788999999997336e-01 */ On Fri, Jul 17, 2009 at 6:41 PM, Maurí­cio wrote:

When we printf doubles from C (like when using hsc2hs to bind to a constant) we can get something that's not valid Haskell. See these 2 examples:

3.40282347e+38F

inf

Do you know some way to printf a double using printf (or any other standard function) that's always going to give me valid Haskell text, even in special cases?

Thanks, Maurício

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