Generalizing Printf in C

3 days ago

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ANSI C89 includes 6 printf functions: printf, sprintf, fprintf, vprintf, vsprintf, vfprintf.
Other C versions add more printf functions like dprintf, snprintf, asprintf, vdprintf, vsnprintf, vasprintf.
The difference between these functions lies in input format and output source.
Proposal to generalize printf functions into one core function to reduce redundancy.
Simple optimizations can reduce the number of functions needed from 12 to 4.
sprintf is discouraged due to security risks, similar to gets.
Three key functions remain: vfprintf, vasprintf, vsnprintf.
Generalizing these into one function is possible but inefficient due to memory usage.
Discussion on qsort in C89, highlighting its use of function pointers and type transmutation.
Example of qsort usage with different array types and the lack of type safety.
Proposal for a printf implementation using function pointers and state management.
Introduction of a struct bufinfo to manage state during buffer writing.
Example implementation of vsnprintf using state management.
Alternative solutions and considerations for future C standards.

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