View Compilation Error

897138_0_0_13773.cpp: In function `int searchMaxSubString(char*)':
897138_0_0_13773.cpp:20: error: `strrev' undeclared (first use this function)
897138_0_0_13773.cpp:20: error: (Each undeclared identifier is reported only once for each function it appears in.)
897138_0_0_13773.cpp: At global scope:
897138_0_0_13773.cpp:34: error: `main' must return `int'