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POSeparating a single string into multiple stacks
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  1. POSeparating a single string into multiple stacks
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    copied!<p>What I am trying to do is take a string, say "((4+2)/2)", and evaluate it, returning 3. I am supposed to do this by separating the string into three separate stacks... one for the open parentheses '(', one for the digits '0' - '9', and one for the operators, '+' '-' '*' '/' and '%'. </p> <p>The issue I am having is actually separating the string into stacks. My code is as follows:</p> <pre><code>//The evaluate function takes a string containing an arithmetic expression, //evaluates it,and returns its result int evaluate(string exp) { stack&lt;char&gt; parStack; stack&lt;int&gt; numStack; stack&lt;char&gt; opStack; int j = exp.size(); int i=0; char x; //for (i=0; i&lt;j; i++) //{ while (i&lt;j) { if(exp[i] = '(') { parStack.push(exp[i]); cout &lt;&lt; exp[i] &lt;&lt; endl; // just to see what is being pushed } if((exp[i]='0') || (exp[i]='1') || (exp[i]='2') || (exp[i]='3') || (exp[i]='4') || (exp[i]='5') || (exp[i]='6') || (exp[i]='7') || (exp[i]='8') || (exp[i]='9')) // I feel this is terribly inefficient { numStack.push(exp[i]); } if((exp[i] = '+') || (exp[i] = '-') || (exp[i] = '*') || (exp[i] = '/') || (exp[i] = '%')) { opStack.push(exp[i]); } i++; } //} // end for return -1; } // end evaluate </code></pre> <p>As you can see, I've tried tackling this with both for loops and while loops, both giving the same result. What happens is, for some reason, if I enter "(5+3)", it prints out "(((((" as what is being pushed. Why is my if statement repeating itself like this? Ignore for now the return -1 at the end, as that will be completed to actually evaluate the string, which I'm sure I can handle, once I can effectively create the stacks.</p>
 

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