View Compilation Error

0_0_21395115_8737.cpp: In function 'int main()':
0_0_21395115_8737.cpp:19:29: error: 'strcmp' was not declared in this scope
         if(!strcmp(a,"START"))
                             ^
0_0_21395115_8737.cpp:34:31: error: 'strcmp' was not declared in this scope
           if(!strcmp(c,"START"))
                               ^
0_0_21395115_8737.cpp:40:29: error: 'strlen' was not declared in this scope
               int l=strlen(c),j=0;
                             ^
0_0_21395115_8737.cpp:45:25: error: 'j' was not declared in this scope
                       d[j++]=c[i];
                         ^
0_0_21395115_8737.cpp:49:25: error: 'j' was not declared in this scope
                       d[j]='\0';
                         ^