isdigit and atoi

[Dan3]

Write your question here.

   Hello,
i don't know what is the field for the function isdigit  and atoi in c++.
Thank you,
 

[48T7M4Gy]

http://www.cplusplus.com/reference/cctype/isdigit/?kw=isdigit
http://www.cplusplus.com/reference/cstdlib/atoi/?kw=atoi

See examples