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POInfix to Postfix notation C++
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  1. POInfix to Postfix notation C++
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    copied!<p>Hello Stack I'm curently atempting to write a RPN converter and I'm new to C++. But I'm running into problems. Hopefully I can explain the problems in detail. Im using an array for stacking my operators. Lets use the example "5 + 8" When I get down to:</p> <pre><code>else if(infix[i] == '+' or infix[i] == '-' or infix[i] == '*' or infix[i] == '/' or infix[i] == '^'){ while(isp(stack1.top()) &gt;= icp(infix[i])){ postfix += stack1.pop(); } if(isp(stack1.top()) &lt; icp(infix[i])){ stack1.push(infix[i]); } </code></pre> <p>For some reason it will push the operator onto the stack but then it wont add the operator to the postfix string variable that im adding my elements too. the out put woul be like "5 8" I looked at my pop function and that seems to be correct but im stumped. if you can lead me in the right direction that would be great.</p> <p>This is my full code:</p> <pre><code>#include &lt;iostream&gt; #include &lt;string&gt; #define DEFAULT_SIZE 100 using namespace std; class Stack{ private: char *array; int tos, capacity; public: //constructors Stack(); //Destructor ~Stack(); //Methods void push(char a); char pop(); char top(); int get_size(); bool is_empty(); bool is_full(); void display(); }; Stack::Stack(){ array = new char[DEFAULT_SIZE]; tos = 0; capacity = DEFAULT_SIZE; } Stack::~Stack(){ delete[] array; } void Stack::push(char a){ if(!is_full()) array[tos++] = a; } char Stack::pop(){ return array[--tos]; } char Stack::top(){ return array[tos]; } int Stack::get_size(){ return tos; } bool Stack::is_empty(){ if(tos == 0) return true; else return false; } bool Stack::is_full(){ if(tos == capacity) return true; else return false; } void Stack::display(){ if (tos == 0) cout&lt;&lt;"The stack is empty"&lt;&lt;endl; else{ for (int i=0; i&lt;tos;i++) cout&lt;&lt;array[i]&lt;&lt;" "; cout&lt;&lt;endl; } } int isp(char a){ if(a == '^'){ return 3; } else if (a == '*' or a == '/'){ return 2; } else if(a == '+' or a == '-'){ return 1; } else if(a == '('){ return 0; } else return -1; } int icp(char a){ if(a == '^'){ return 4; } else if (a == '*' or a == '/'){ return 2; } else if(a == '+' or a == '-'){ return 1; } else if(a == '('){ return 4; } } int main(){ string infix, postfix; Stack stack1; cout &lt;&lt; "This is a Infix to Postfix Expression converter." &lt;&lt; endl; cout &lt;&lt; "Enter your Infix Expression: "; cin &gt;&gt; infix; stack1.push('#'); for(int i=0;i&lt;infix.length();i++){ if(isdigit(infix[i]) or isalpha(infix[i])){ postfix += infix[i]; } else if(infix[i] == '+' or infix[i] == '-' or infix[i] == '*' or infix[i] == '/' or infix[i] == '^'){ while(isp(stack1.top()) &gt;= icp(infix[i])){ postfix += stack1.pop(); } if(isp(stack1.top()) &lt; icp(infix[i])){ stack1.push(infix[i]); } } } cout &lt;&lt; postfix; return 0; } </code></pre> <p>Also if you know anygood resource sites on C++ RPN converter feel free to share because it would be a very big help! Im going off a random algo. that I found on google.</p>
 

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