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POinfix to postfix converter using stack
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  1. POinfix to postfix converter using stack
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    copied!<p>I want to convert infix to postfix expression. This is my code:</p> <p>The problem is that this actually doesn't do so and I am confused why. Everything makes sense to me but when i input for example <code>4*5</code> as an output i get the same thing. infix is an input and postfix is what i want to return as a pointer to postfix so it can be then evaluated.</p> <p>operand returns true if it is * - + or /</p> <p>UPDATE:</p> <p>oki i got it working but i have trouble figuring out what if you input like 5 * 3 + -1.2 then its not gonna work if you want to have like negative number.</p> <pre><code>void infix2postfix(char* infix, char* postfix){ char *in,*post; Stack&lt;char&gt;Q; char n; in = &amp;infix[0]; post = &amp;postfix[0]; while(*in){ while(*in == ' ' || *in == '\t'){ in++; } if( isdigit(*in) || isalpha(*in) ){ while( isdigit(*in) || isalpha(*in)){ *post = *in; post++; in++; } } if( *in == '(' ){ Q.Push(*in); in++; } if( *in == ')'){ n = Q.Pop(); while( n != '(' ){ *post = n; post++; n = Q.Pop(); } in++; } if( operand(*in) ){ if(Q.IsEmpty()) Q.Push(*in); else{ n = Q.Pop(); while(priority(n) &gt;= priority(*in)){ *post = n; post++; n = Q.Pop(); } Q.Push(n); Q.Push(*in); } in++; } } while(!Q.IsEmpty()) { n = Q.Pop(); *post = n; post++; } *post = '\0'; } </code></pre> <p>here is my code new code, it works but I want it to to work with unary operators so it would take the input <code>4 * 5 + 4 + -1.2</code>, so there is a space between and if there is not then it is for example -1.2 negative number. also my code doesn't work for an integer which is more than 9, if i put 10 then it just multiplies 1*0. .</p>
 

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