View Compilation Error

0_0_9735209_29530.cpp: In function `void fac()':
0_0_9735209_29530.cpp:10: error: `itoa' undeclared (first use this function)
0_0_9735209_29530.cpp:10: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9735209_29530.cpp:11: error: `strstr' undeclared (first use this function)