I have some code that uses a stack to convert from infix to postfix. what I want is to also be able to evaluate the postfix expression after the conversion and to convert multiple numbers and floating point numbers.

#include

#include

#include

using namespace std;

//Function to return precedence of operators

int prec(char c)

{

if(c == '^')

return 3;

else if(c == '*' || c == '/')

return 2;

else if(c == '+' || c == '-')

return 1;

else

return -1;

}

// The main function to convert infix expression

//to postfix expression

void infixToPostfix(string s)

{

std::stack st;

st.push('N');

int l = s.length();

string ns;

for(int i = 0; i < l; i++)

{

// If the scanned character is an operand, add it to output string.

if((s[i] >= 'a' && s[i] <= 'z')||(s[i] >= 'A' && s[i] <= 'Z'))

ns+=s[i];

// If the scanned character is an (, push it to the stack.

else if(s[i] == '(')

st.push('(');

// If the scanned character is an ), pop and to output string from the stack

// until an ( is encountered.

else if(s[i] == ')')

{

while(st.top() != 'N' && st.top() != '(')

{

char c = st.top();

st.pop();

ns += c;

}

if(st.top() == '(')

{

char c = st.top();

st.pop();

}

}

//If an operator is scanned

else{

while(st.top() != 'N' && prec(s[i]) <= prec(st.top()))

{

char c = st.top();

st.pop();

ns += c;

}

st.push(s[i]);

}

}

//Pop all the remaining elements from the stack

while(st.top() != 'N')

{

char c = st.top();

st.pop();

ns += c;

}

cout << ns << endl;

}

//Driver program to test above functions

int main()

{

string exp = "a+b*(c^d-e)^(f+g*h)-i";

infixToPostfix(exp);

return 0;

}