View Compilation Error

0_0_13981822_19084.cpp: In function 'int main()':
0_0_13981822_19084.cpp:41:22: error: 'strcpy' was not declared in this scope
      strcpy(c1,sum[i]);
                      ^
0_0_13981822_19084.cpp:42:18: error: 'strlen' was not declared in this scope
      l1=strlen(c1);l2=strlen(c2);
                  ^