Float string representation precision problems

Submitted by G??bor Szalai

The string representation of the TTCN-3 floats are not precise enough. Less significant digits are used than required.

Examples: Code generation problems: TTCN code

var float fl:= 1.0000000000000002 // smallest value greater than 1 representable by 64bit double

Generated C++ code: fl = 1;

Other problematic example: 3.2511111111111113e123

The same precision problem exists in: string2ttcn JSON encoder float2str

The number of the needed significant digits are depends on the used floating point type. In the case of the double at least 17 digits are needed.

Version: 7.1.0