int main()
{
Expression* infix;
Expression* postfix;
std::string* evaluatedExpression;
char newline[80];
char nextChar;
std::fstream expressions;
expressions.open("TestExpressions.txt");
infix = new Expression;
infix->read(expressions);
while(expressions.good())
{
postfix = new Expression;
evaluatedExpression = new std::string;
infix->print(std::cout);
convertToPostfix(*infix, *postfix);
postfix->print(std::cout);
evaluatePostfix(*postfix, *evaluatedExpression);
std::cout << *evaluatedExpression << "\n";
delete infix;
delete postfix;
delete evaluatedExpression;
expressions.getline(newline, 79, '\n'); // move past end of line
nextChar = expressions.peek(); // peek next character to check if at end of file
infix = new Expression;
infix->read(expressions);
}
delete infix;
expressions.close();
return 0;
}
int main(void){
char str[100], input[100];
// Prints Intro
printf("Simple Calculator\n");
// Prints the input prompt, along with goto label to jump back to input
inputPrompt:
printf(">>>");
fgets(str,sizeof(str),stdin);
sscanf(str, "%[^\n]",input);
// printf("The input is: %s\n",input);
/* Checks to see if the user wants to quit */
if(strcmp(input, "q") == 0 || strcmp(input,"Q") == 0){
printf(" Goodbye!");
exit(0);
}
/* Checks to see if the user asked for help */
else if(strcmp(input,"h") == 0 || strcmp(input,"H") == 0){
printhelp();
}
/* If the string entered has passed all pre-checks, then send off to functions dealing with arithmetic */
else{
/* Send the user input to the function that will standardise the whitespaces to use as delimiters
* (make sure there is only ever one whitespace at most) */
standardiseWhitespaces(input);
// printf("After White spaces: %s\n",input);
/* Run through a bunch of checks, print an error message and go back to the input prompt if something is found */
if(operatorsIncorrect(input) == TRUE || tooManyPoints(input) == TRUE || invalidCharacters(input) == TRUE) {
printf(" Error: Illegal input!\n");
goto inputPrompt;
}
if(divideByZero(input) == TRUE){
printf(" Error: Divide by zero!\n");
goto inputPrompt;
}
/* Converts any e's to scientific notation */
convertFromScientificNotation(input);
// printf("After Scientific Notation: %s\n",input);
/* Put string through function to turn it in to post-fix notation */
convertToPostfix(input);
// printf("After postfix: %s\n",input);
/* Puts the postfix notation string in to the arithmetic function, which then interprets the equation, solves it , then prints it */
printf(" %lf\n",arithmetic(input));
}
/* Goes to the start of the program where it prompts for input */
goto inputPrompt;
}
int main(int argc, char const *argv[])
{
char infix[40]="(6+2)*5-8/4";
char postfix[40]="";
convertToPostfix(infix,postfix);
printf("%s\n",postfix );
return 0;
}
int compute(char* infix){
//allocate string (80 chars)
char *postfix = malloc(80 * sizeof(char));
//convert to postfix
convertToPostfix(infix, postfix);
//compute answer
return computePostfix(postfix);
}
int main(void)
{
char infix[50] = {'(','3','-','1',')','*','8','+','2','\0'};
char infix2[50];
char postfix[50] = {'\0'};
int i = 0, result = 0;
char cont = 'y';
while (toupper(cont) == 'Y')
{
//Clear infix2
for(i = 0; i < 50; i++)
{
infix2[i] = '\0';
}
//Clear postfix
for(i = 0; i < 50; i++)
{
postfix[i] = '\0';
}
//Get expression from user
_flushall();
printf("Enter an expression to convert to postfix (no spaces): ");
gets(infix2);
//Convert to postfix
convertToPostfix(infix2, postfix);
//Print postfix expression
printf("\nPostfix: ");
i = 0;
while(postfix[i] != '\0')
{
printf("%c ", postfix[i]);
i++;
}
//Calculate result using postfix expression
result = evaluatePostfixExpression(postfix);
//Print result
printf("\nResult: %d\n", result);
do{
_flushall();
printf("\nWould you like to continue? <Y or N>: ");
scanf("%c", &cont);
if(toupper(cont) != 'Y' && toupper(cont) != 'N')
{
printf("Invalid option, please choose Y or N\n");
}
}while(toupper(cont) != 'Y' && toupper(cont) != 'N');
}
return 0;
}
int main(int argc, char const *argv[])
{
printf("Enter the infix expression.\n");
char infix[MAXSIZE]; //defines char array to read input into
scanf("%s",infix); //reads in infix string from user
char postfix[MAXSIZE];
printf("The original infix expression is:\n%s\n",infix);
convertToPostfix(infix,postfix);
printf("The expression in postfix notation is:\n%s\n",postfix);
return 0;
}
// evaluate
// Evaluates the entire expression
// Parameters:
// expression (input string) the expression to evaluate
// Pre-condition: The expression is correctly formatted
// Return: Value of the expression
int evaluate(const char expression[])
{
TokenList expr(expression), //Original expression
postExpr, //Expression converted to postfix
numberStack; //Stack of numbers to facilitate evaluation
//Converts expr into postfix and store it into postExpr
convertToPostfix(expr, postExpr);
std::cout << "Original expression: " << expr << std::endl;
std::cout << "Converted postfix expression: " << postExpr << std::endl;
for (ListIterator iter = postExpr.begin(); iter != postExpr.end(); iter.advance())
{
Token t = iter.token();
if (t.isInteger())
{
numberStack.push_front(t);
}
else
{
//This is the huge bit that handles operators
//val2 is created but uninitialized to handle binary operators and
//unary operators ('~') easily in the same switch
int value = numberStack.pop_front().integerValue();
int val2 = 0;
switch (t.tokenChar())
{
case '*':
val2 = numberStack.pop_front().integerValue();
val2 *= value;
numberStack.push_front(Token(val2));
break;
case '/':
val2 = numberStack.pop_front().integerValue();
val2 /= value;
numberStack.push_front(Token(val2));
break;
case '%':
val2 = numberStack.pop_front().integerValue();
val2 %= value;
numberStack.push_front(Token(val2));
break;
case '+':
val2 = numberStack.pop_front().integerValue();
val2 += value;
numberStack.push_front(Token(val2));
break;
case '-':
val2 = numberStack.pop_front().integerValue();
val2 -= value;
numberStack.push_front(Token(val2));
break;
case '~':
value = -value;
numberStack.push_front(Token(value));
break;
}
}
}
//Value left on the top of the number stack is the final value of the expression
return numberStack.pop_front().integerValue();
}
