Infix to Postfix cprogram

aim: to implement a infix to post fix c-program:

program:

#include<ctype.h>

#include<stdio.h>

char stack[80];

int top=-1;

char pop();

void main()

{

char instring[80],outstring[80];

int l,p=0,i;

clrscr();

printf("Enter the infix expression\n");

scanf("%s",instring);

l=strlen(instring);

for(i=0;i<l;i++)

{

if((toupper(instring[i])>='A')&&(toupper(instring[i])<='Z'))

outstring[p++]=toupper(instring[i]);

else if(instring[i]=='(')

push(instring[i]);

else if(instring[i]==')')

{

while(stack[top]!='(')

outstring[p++]=pop();

pop();

}

else

{

while(stack_preced(stack[top])>=in_preced(instring[i]))

outstring[p++]=pop();

push(instring[i]);

}

}

while(top>=0)

outstring[p++]=pop();

outstring[p--]='\0';

printf("postfix expresion=%s",outstring);

getch();

}

stack_preced(char x)

{

switch(x)

{

case '+':

case '-':return(1);

case '*':

case '/':return(2);

case '$':return(3);

case '(':return(0);

}

}

in_preced(char x)

{

switch(x)

{

case '+':

case '-':return(1);

case '*':

case '/':return(2);

case '$':return(3);

case '(':return(4);

}

}

push(char c)

{

stack[++top]=c;

}

char pop()

{

char c;

c=stack[top];

top--;

return(c);

}