Simple techniques for converting infix expressions to pre- and postfix expressions [transfer]

Original source https://www.cnblogs.com/Hslim/p/5008460.html

Here I give an infix expression

1	a+b*c-(d+e)    //中缀表达

Step 1: Add parentheses to all operational units according to the operator's precedence

            The formula becomes: ((a+(b*c))-(d+e))
Step 2: Convert the prefix and postfix Expression
        prefix: Move the operator to the front of the corresponding parenthesis and
                it becomes: -( +( a *(bc)) +(de)) //
                Remove the parentheses when moving here: -+a*bc+de   prefix expression appears
        suffix: move the operator symbol after the corresponding parenthesis to
                become: ((a( bc)* )+ (de)+ )
                -Remove the parentheses: abc*+de+- If the    suffix expression appears
, it is found that there is no, prefix type, suffix type do not need parentheses to determine the priority.
//Look at the rules yourself