View Compilation Error

0_0_29283857_5890.cpp:2:16: error: 'string' was not declared in this scope
 bool is_reback(string& str)
                ^
0_0_29283857_5890.cpp:2:24: error: 'str' was not declared in this scope
 bool is_reback(string& str)
                        ^
0_0_29283857_5890.cpp:3:1: error: expected ',' or ';' before '{' token
 {
 ^