Inside Macintosh: PowerPC Numerics / Part 3 - Appendixes

Appendix B - Porting Programs to PowerPC Numerics

Mixed Formats

On certain computers, the formats for single and double are identical except for their length. On those machines, for arguments passed by address, a calling routine can store data in one format and a called routine can read data in another format without apparent error.

If you have a program that exploits this confusion, you'll have to revise it before you can run it on a machine that uses PowerPC Numerics. (Type checking is of no help here; if the discrepancy was such that type checking could detect it, the original compiler would have caught it.)