I want to be able to evaluate an expression typed by the user (ie 23+5-4, 23-4-5, 2+5+6+7 etc...any length). The expression contains only integers, '+', and '-' (no parentheses). I have worked on the following for a hours now...it crashes when I run it after it prompts for the input. I do not know what is wrong. Can anyone tell me what is wrong with my code ( I am programming in VC++ --which later I have to make g++ compatible). Thanks very much. -chanthee

(You must forgive me if this looks ugly...but I don't know how to set tags...I've never posted before)

Code:#include <iostream> #include <cstring> #include <cstdlib> #include <cctype> #include <stack> using namespace std; int read_and_evaluate(istream& ins); void evaluate_expression(stack<int>& numbers, char& symbol); int main() { int answer; cout << "Enter an arithmetic expression: "<< endl; answer = read_and_evaluate(cin); cout << "The answer is "<< answer << endl; return EXIT_SUCCESS; } int read_and_evaluate(istream& ins) { stack<int> numbers; int number; char symbol; do { if (isdigit(ins.peek())) { ins >> number; numbers.push(number); } else { ins >> symbol; evaluate_expression( numbers, symbol); } } while (ins && ins.peek() != '\n'); return numbers.top(); } void evaluate_expression(stack<int>& numbers, char& symbol) { int operand2, operand1; operand2 = numbers.top(); numbers.pop(); operand1 = numbers.top(); numbers.pop(); switch(symbol) { case '+': numbers.push(operand1 + operand2); break; case '-': numbers.push(operand1 - operand2); break; } }Code tags added by Kermi3