View Compilation Error

0_0_26139729_16353.cpp: In function 'void Insert()':
0_0_26139729_16353.cpp:21:26: error: 'strlen' was not declared in this scope
     int len = strlen(tstr);
                          ^
0_0_26139729_16353.cpp: In function 'int Find()':
0_0_26139729_16353.cpp:70:24: error: 'strlen' was not declared in this scope
     int len=strlen(tstr);
                        ^