View Compilation Error

0_0_30338908_13549.cpp: In function 'void quicksort(char**, int, int)':
0_0_30338908_13549.cpp:19:29: error: 'strcmp' was not declared in this scope
   while(strcmp(p[start],temp) < 0)
                             ^
0_0_30338908_13549.cpp:21:27: error: 'strcmp' was not declared in this scope
   while(strcmp(temp,p[end]) <= 0)
                           ^
0_0_30338908_13549.cpp: In function 'int main()':
0_0_30338908_13549.cpp:53:25: error: 'strcmp' was not declared in this scope
    if(strcmp(p[i],p[i+1]) == 0)
                         ^