C program to perform Prefix to Postfix evaluation.

#include<stdio.h>

#include<conio.h>

#include<stdlib.h>

#include<math.h>

#include<string.h>

 int chartoint(char c)

{

    return (c-48);

}

int operation(int op1,int op2, char op)

{

    switch(op)

    {

            case '+':

                return op1+op2;

            case '-':

                return op1-op2;

            case '*':

                return op1*op2;

            case '/':

                return op1/op2;

            case '^':

                return pow(op1,op2);

    }

    return -1;

}

int main()

{

    int op1,op2,st[20],i=-1,j=-1;

    char op,exp[20];

    clrscr();

    printf("\nEnter prefix expression\n");

    scanf("%s",exp);

    for(i=strlen(exp)-1;i>=0;i--)

    {

            if(exp[i]=='+'||exp[i]=='-'||exp[i]=='*'||exp[i]=='/'||exp[i]=='^')

            {

                op=exp[i];

                op1=st[j];

                j--;

                op2=st[j];

                st[j]=operation(op1,op2,op);

            }

            else

            {

                j++;

                st[j]=chartoint(exp[i]);

            }

    }

    printf("\nThe answer is : %d\n",st[0]);

   getch();

    return 0;

}

Output: