View Compilation Error

0_0_1987176_26134.cpp: In function `int main()':
0_0_1987176_26134.cpp:6: error: `scanf' undeclared (first use this function)
0_0_1987176_26134.cpp:6: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1987176_26134.cpp:6: error: `gets' undeclared (first use this function)
0_0_1987176_26134.cpp:6: error: `strrev' undeclared (first use this function)
0_0_1987176_26134.cpp:6: error: `puts' undeclared (first use this function)