View Compilation Error

0_0_23889939_9946.cpp: In function 'void format(char*)':
0_0_23889939_9946.cpp:27:33: error: 'strlen' was not declared in this scope
     int i=0,j,len=0,n=strlen(dst);  
                                 ^
0_0_23889939_9946.cpp:28:15: error: 'strlwr' was not declared in this scope
     strlwr(dst);  
               ^
0_0_23889939_9946.cpp: In function 'int main()':
0_0_23889939_9946.cpp:62:45: error: 'strcpy' was not declared in this scope
             strcpy(text[i].low,text[i].title);  
                                             ^
0_0_23889939_9946.cpp:84:43: error: 'strstr' was not declared in this scope
                 if (strstr(text[j].low,src))  
                                           ^