View Compilation Error

0_0_21438947_18627.cpp: In function 'bool kmp(char*, char*)':
0_0_21438947_18627.cpp:26:32: error: 'strlen' was not declared in this scope
  int textLen = (int)strlen(text);
                                ^
0_0_21438947_18627.cpp: In function 'int main()':
0_0_21438947_18627.cpp:52:16: error: 'scanf' was not declared in this scope
  scanf("%d", &T);
                ^
0_0_21438947_18627.cpp:58:24: error: 'strlen' was not declared in this scope
    if(strlen(strings[i]) < minLen){
                        ^
0_0_21438947_18627.cpp:88:24: error: 'printf' was not declared in this scope
   printf("%d\n", maxAns);
                        ^