3rd-prog-in-data-structures

in this program i wanted to learn about expressions and how to convert them so i build a program to convert 4 cases
1- to convert from postfix to infix 2- to convert from prefix to infix 3- to convert from infix to prefix 4- to convert from infix to postfix. infix: its expression which have operators and operands normally beside each others. prefix: its expression where the operators comes first the the operands. postfix: its opposite prefix the operands comes first then the operators. examples: (1)infix: a+b , in prefix: +ab , in postfix: ab+ . (2)infix: (a+b)c , in prefix: +(ab)c , in postfix: ab+c. (3)infix: (a-b/c)(a/k-l) , in prefix: -a/bc/a-kl , in postfix:ab-c/ak/l- that's all i hope to find my program usefull good luck.