atoi() function where does it come from ?

Docedison:
Tom Carpenter... Does that also include "sprintf"?

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In the past when I did compilers for other embedded processors, the problem with using any of the *printf functions is they pull in the whole floating point and long long arithmetic support functions. On some of the ports, *printf would use 3/4 of the total memory for all of the support functions. So, the functions are convenient to use, but they can be big.