Aim: Infix to Postfix
Steps:
1. Input the infix string
2. The program use the stack implementation to convert this infix to postfix
3. There are 5 function are used
Pop() is used to pop the elements
Push() is used to push the element in the stack
createstack() is used to create head node
check() is used to test whether the element has to push or print
priority() is used to check the priority of the operators
output
Steps:
1. Input the infix string
2. The program use the stack implementation to convert this infix to postfix
3. There are 5 function are used
Pop() is used to pop the elements
Push() is used to push the element in the stack
createstack() is used to create head node
check() is used to test whether the element has to push or print
priority() is used to check the priority of the operators
output
Program
#include<stdio.h>
int priority(char a);
int check(char a);
typedef struct node
{
void *data;
struct node *link;
}stacknode;
typedef struct
{
int count;
stacknode *top;
}stack;
stack *createstack()
{
stack *sp;
sp=(stack*)malloc(sizeof(stack));
sp->top=NULL;
sp->count=0;
}
void push(stack *sp,void *data)
{
stacknode *node;
node=(stacknode*)malloc(sizeof(stacknode));
node->data=data;
node->link=sp->top;
sp->top=node;
sp->count++;
}
void *pop(stack *sp)
{
stacknode *temp;
void *data;
data=sp->top->data;
temp=sp->top;
sp->top=sp->top->link;
free(temp);
sp->count--;
return(data);
}
void *top(stack *sp)
{
return(sp->top->data);
}
int main()
{
stack *sp;
char s[100];
int i;
int j;
char *a;
sp=createstack();
printf("\nenter the string\n");
scanf("%s",s);
for(i=0;i<=strlen(s);i++)
{
if(check(s[i]))
{
printf("%c",s[i]);
}
else if(s[i]==')')
{
while(*(char*)top(sp)!='(')
{
a=(char*)pop(sp);
printf("%c",*a);
free(a);
}
a=(char*)pop(sp);
free(a);
}
else
{
if(s[i]=='(')
{
a=(char*)malloc(sizeof(char*));
*a=s[i];
push(sp,a);
}
else
{
if(s[i]=='('||priority(*(char*)top(sp))<priority(s[i]))
{
a=(char*)malloc(sizeof(char*));
*a=s[i];
push(sp,a);
}
else
{
a=(char*)pop(sp);
printf("%c",*a);
free(a);
while(priority(*(char*)top(sp))>=priority(s[i])&&*(char*)pop(sp)!='(')
{
a=(char*)pop(sp);
printf("%c",*a);
free(a);
}
if(!check(s[i]))
{
a=(char*)malloc(sizeof(char*));
*a=s[i];
push(sp,a);
}
}
}
}
}
free(s);
free(sp);
getch();
return(0);
}
int priority(char a)
{
switch(a)
{
case '(': return(-1);
break;
case '/': return(1);
break;
case '*': return(1);
break;
case '-': return(0);
break;
case '+': return(0);
}
return(0);
}
int check(char a)
{
if(a=='*'||a=='/'||a=='-'||a=='+'||a=='('||a==')')
{
return(0);
}
else
{
return(1);
}
}
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