new c lib: scanf of floats %aefg unsupported

[aralbrec]

In the new c lib you can printf floats but you can't scanf them. The recommended workaround is to first scan as a string using %s or %[ and then use strtod() or atof() to do the float conversion.

What is missing is a state machine in the stdio library that examines an incoming char stream and decides where a float ends. This is complicated by the fact that floats can take on a number of forms:

• 123
• 123.
• .
• .123
• 123.123
• variations with exponent e
• hex floats 0xabc.123P-28
• special strings "nan", "infinity" etc

[suborb]

There's code that handles the common cases in the classic library - we read from the file and put it into a temporary buffer on the stack which atof() then parses. It's in libsrc/stdio/__scanf_handle_f.asm

It follows the 99% rule so would need extension for the new library, but could be a quick win whilst you work on full c99 compatibility.

[aralbrec]

Yes maybe a temporary partial solution is ok. The underlying implementation of strtod/atof in the new c lib can do all the float formats listed above so it just needs a buffer to act on that is gathered by scanf. But maybe a %f only solution can be implemented for the decimal float case so that a simple state machine can be employed.