View Compilation Error

0_0_17111982_12261.cpp: In function 'int main()':
0_0_17111982_12261.cpp:10:24: error: 'strcmp' was not declared in this scope
         if(strcmp(a,"0")==0)break;
                        ^
0_0_17111982_12261.cpp:11:25: error: 'strlen' was not declared in this scope
         int len=strlen(a);
                         ^