View Compilation Error

0_0_18707229_11088.cpp: In function 'void dfs(int, int)':
0_0_18707229_11088.cpp:9:21: error: 'strlen' was not declared in this scope
     if(x==strlen(seq))
                     ^
0_0_18707229_11088.cpp:15:29: error: 'strlen' was not declared in this scope
     for(int i=x;i<strlen(seq);i++)
                             ^