View Compilation Error

0_0_19883834_4561.cpp: In function 'int num(char*)':
0_0_19883834_4561.cpp:6:22: error: 'strcmp' was not declared in this scope
   if(strcmp(a[i],temp)==0){
                      ^
0_0_19883834_4561.cpp: In function 'int main(int, char**)':
0_0_19883834_4561.cpp:17:42: error: 'strcmp' was not declared in this scope
   while(scanf("%s",str1)&&strcmp(str1,"+")!=0){
                                          ^
0_0_19883834_4561.cpp:20:42: error: 'strcmp' was not declared in this scope
   while(scanf("%s",str2)&&strcmp(str2,"=")!=0){
                                          ^