KITFORMA · EDITORIAL GUIDE
Why does scanf with %f corrupt a double variable?
KitForma editorial guide. Input formatting writes through a pointer, so the pointed-to type must match the conversion. For scanf, `%f` expects float storage while `%lf` expects double storage.
Step-by-step guidance
Input formatting writes through a pointer, so the pointed-to type must match the conversion. For scanf,
%f expects float storage while %lf expects double storage.
Match the conversion to the destination declaration and pass its address. Check the assignment count before using the value. Do not transfer printf rules directly to scanf: variadic output promotions and pointer-based input are different contracts.
Test an ordinary decimal, malformed input and out-of-range text with strict format warnings. For robust validation, line input plus an explicit conversion function can provide clearer range and suffix checks. Merely allocating a larger destination does not make an incompatible pointer format safe.Sources and verification
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