View Compilation Error

0_0_36402982_11400.cpp: In function 'int main()':
0_0_36402982_11400.cpp:41:30: error: 'strlen' was not declared in this scope
         for (i=0;i<strlen(str)-1;i++)
                              ^
0_0_36402982_11400.cpp:48:30: error: 'strlen' was not declared in this scope
         for (i=0;i<strlen(str)-1;i++)
                              ^
0_0_36402982_11400.cpp:55:30: error: 'strlen' was not declared in this scope
         for (i=0;i<strlen(str);i++)
                              ^