View Compilation Error

0_0_9957534_20923.cpp: In function `int main()':
0_0_9957534_20923.cpp:12: error: `isalpha' undeclared (first use this function)
0_0_9957534_20923.cpp:12: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9957534_20923.cpp:17: error: `isalnum' undeclared (first use this function)