void Postfix_Evaluator_Strategy::Build_Expression_Strategy()
{
bool quit=false;
bool converted=false;
std::ifstream Exprfile;
Exprfile.open("testExpressions.txt");
clock_t t;
t=clock();
do
{
Array<Command *> postfix;
std::string infix;
Stack_Expr_Command_Factory factory;
try
{
quit = false;
int result=0;
getline(Exprfile, infix);
if (infix.compare("QUIT") == 0)
{
quit = true;
break;
}
//call infix_to_postfix
converted = infix_to_postfix(infix, factory, postfix);
if(converted)
{
Array_Iterator<Command *> arr_iter(postfix);
if(evaluate_postfix(arr_iter, result))
std::cout <<"\nExpression Value : " <<result;
}
else
{
std::cout<<"\nInvalid expression";
}
}
catch(std::exception &e)
{
std::cout<<e.what()<<"\n";
}
}
while(!quit);
t= (float)(clock()-t)/(CLOCKS_PER_SEC/1000);
cout<<"\n Time : "<<t<<" millisecs";
Exprfile.close();
}
int main( int argc, char* argv[] )
{
char* string;
string = malloc(100*sizeof(char));
int answer;
fgets(string, 100*sizeof(char), stdin);
answer = evaluate_postfix(string);
// printf("%d",answer);
return 0;
}
int main(void) {
while(fgets(buf, MAX_LEN, stdin) != NULL) {
buf[strcspn(buf, "\n")] = '\0';
if(!strncmp(buf, "\0", 1)) continue;
if(!strncmp(buf, "0\0", 2)) break;
if(match_parentheses(buf)) { printf("Incorrectly matched parentheses\n"); continue;}
normalize_exp(buf);
if(infix2postfix(buf)) continue;
printf("%d\n", evaluate_postfix(buf));
}
}
/* returns the final answer */
double evaluate(const char * str) {
char * strbuffer; /* mutable buffer for string (modified in calls to strtok()) */
double ans; /* answer to return */
struct token_queue queue_infix, queue_postfix;
/* copy str into mutable buffer */
strbuffer = strcpy((char *)malloc(strlen(str)+1),str);
/* get queue of tokens in infix order from string buffer */
queue_infix = expr_to_infix(strbuffer);
/* get queue of tokens in postfix order from infix-ordered queue */
queue_postfix = infix_to_postfix(&queue_infix);
/* get answer from postfix-ordered queue */
ans = evaluate_postfix(&queue_postfix);
free(strbuffer); /* free memory from heap */
return ans;
}
