View Compilation Error

0_0_15689170_8805.cpp: In function 'int main()':
0_0_15689170_8805.cpp:13:19: error: 'strlen' was not declared in this scope
 for(m=0;m<strlen(s);m++)
                   ^
0_0_15689170_8805.cpp:16:5: error: expected primary-expression before ';' token
 sum+;
     ^