View Compilation Error

0_0_32287092_6244.cpp: In function 'int main()':
0_0_32287092_6244.cpp:20:29: error: 'strlen' was not declared in this scope
         for(j=0;j<strlen(str);j++){
                             ^
0_0_32287092_6244.cpp:33:26: error: 'strlen' was not declared in this scope
         for(;j<strlen(str);j++){
                          ^