View Compilation Error

0_0_1109395_20734.cpp: In function `int main()':
0_0_1109395_20734.cpp:17: error: `strrev' undeclared (first use this function)
0_0_1109395_20734.cpp:17: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1109395_20734.cpp: In function `int main()':
0_0_1109395_20734.cpp:29: error: redefinition of `int main()'
0_0_1109395_20734.cpp:6: error: `int main()' previously defined here
0_0_1109395_20734.cpp:40: error: `strrev' undeclared (first use this function)