Program to convert Infix to Prefix Method 1 ~ Coding Atharva

/* INfix to Prefix
Method 1
left to right
1.do same as postfix 3 minor change:
1 Equal Priority
2 ')' closing direct push
3 '(' pop till closing came
2.reverse the final answer
*/
#include<stdio.h>
#include<conio.h>
#include<ctype.h>
#include<string.h>
#define SIZE 100

typedef struct STACK
{
char data[SIZE];
int top;

}stack;

void intialize(stack *s);
void push(stack *s,char ch);
char pop(stack *s);
int priority(char ch);
void intopre(stack *s,char infix[]);

int main()
{
char infix[SIZE];
int i;
stack s;

printf("\n\n Enter the infix string: ");
scanf("%s",infix);

intopre(&s,infix);

return 0;
}

void intialize(stack *s)
{
s->top=-1;
}
void push(stack *s,char ch)
{
if(s->top != SIZE-1 )
{
s->top++;
s->data[s->top]=ch;
}
}
char pop(stack *s)
{
char ch;
if(s->top != -1)
{
ch=s->data[s->top];
s->top--;
return ch;
}
return 0;
}
int priority(char ch)
{
switch(ch)
{
case '^':
return 3;
break;
case '%':
case '/':
case '*':
return 2;
break;
case '+':
case '-':
return 1;

default: return 0;
}
}
void intopre(stack *s,char infix[])
{
char prefix[SIZE],ch;
int length,i,j=0,k;

intialize(s);
push(s,'#');

length=strlen(infix);

for(i=length-1;i>=0;i--)
{
ch=infix[i];

if(ch==')')
{
push(s,ch);
}
else if(isalnum(ch))
{
prefix[j]=ch;
j++;
}
else if(ch=='(')
{
while(s->data[s->top] != ')')
{
prefix[j]=pop(s);
j++;
}
s->top--;
}
else
{
while(priority(ch)<priority(s->data[s->top]))
{
prefix[j]=pop(s);
j++;
}
push(s,ch);
}
}
while(s->data[s->top] != '#' )
{
prefix[j]=pop(s);
j++;
}
prefix[j]='\0';
strrev(prefix);
printf("\n\n The Prefix String: %s",prefix);
}

Program to convert Infix to Prefix Method 1

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