#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int n;
int stackfull(int top)
{
if(top==n)
{
return 1;
}
else
{
return 0;
}
}
int stackempty(int top)
{
if(top==-1)
{
return 1;
}
else
{
return 0;
}
}
int push(char stack[],int top,int data)
{
if(!stackfull(top))
{
top+=1;
stack[top]=data;
}
else
{
printf("Stack full!");
}
}
int pop(char stack[],int top)
{
if(!stackempty(top))
{
char data=stack[top];
top--;
return data;
}
/*else
{
printf("Stack empty!");
}*/
}
void getstr(char a[])
{
for(int i=0;i<70;i++)
{
char c;
scanf("%c",&c);
if(c=='\n')
{
a[i]='\0';
break;
}
else{
a[i]=c;
}
}
}
int operator(char o)
{
int r=0;
if(o=='+'||o=='-'||o=='*'||o=='/'||o=='$')
{
r=1;
}
return r;
}
int priority(char o)
{
int r;
switch(o)
{
case '+': r= 1;
break;
case '-': r= 1;
break;
case '*': r= 2;
break;
case '/': r= 2;
break;
case '$': r= 3;
}
return r;
}
int intopost(char a[],char out[])
{
int i=0,j=0,top=-1;
char stk[n];
while(a[i]!='\0')
{
if(operator(a[i]))
{
if(stackempty(top))
{
push(stk,top,a[i]);
top++;
}
else
{
if(stk[top]=='('||priority(a[i])>priority(stk[top]))
{
printf("\t2=%s %s\t",stk,out);
push(stk,top,a[i]);
top++;
}
else if(priority(a[i])<priority(stk[top])||priority(a[i])==priority(stk[top]))
{
printf("\t2=%s %s\t",stk,out);
out[j]=pop(stk,top);
top--;
j++;
push(stk,top,a[i]);
top++;
}
}
}
else if(a[i]=='(')
{
push(stk,top,a[i]);
top++;
}
else if(a[i]==')')
{
while (stk[top]!='(')
{
if(stackempty(top)&&stk[top]=='(')
{
return -1;
}
else
{
out[j] = pop(stk,top);
j++;
}
top--;
}
char ch=pop(stk,top);
top--;
}
else if((a[i]>='a'&&a[i]<='z')||(a[i]>='A'&&a[i]<='Z'))
{
out[j]=a[i];
j++;
}
i++;
}
while(stackempty(top));
{
out[j]=pop(stk,top);
j++;
top--;
}
if(!stackempty(top))
{
out[j]=pop(stk,top);
j++;
top--;
}
out[j]='\0';
j++;
}
int main()
{
char s[70],o[70],ch;
int i,f;
printf("Enter the expression:");
getstr(s);
printf("%s -> ",s);
n=strlen(s);
intopost(s,o);
printf("%s",o);
}
I was writing this program which should convert infix expression to postfix expression but it is not working in case of a+(b-c)*d$e/f+g$(h-i) as input. The output comes out to be abc-de$f/ghi-$+ but the output should be abc-de^*f/+ghi-^+. An asterisk is missing in the code's output.
I found the solution:
#include<stdio.h>
int n,top=-1;
char stk[50];
int stackfull()
{
if(top==n)
{
return 1;
}
else
{
return 0;
}
}
int stackempty()
{
if(top==-1)
{
return 1;
}
else
{
return 0;
}
}
void push(char data)
{
if(!stackfull())
{
top++;
stk[top]=data;
}
else
{
printf("Stack full!");
}
}
char pop()
{
if(!stackempty())
{
char data=stk[top];
stk[top]=' ';
top--;
return data;
}
else
{
printf("Stack empty!");
}
}
void getstr(char a[])
{
int i;
for(i=0;i<70;i++)
{
char c;
scanf("%c",&c);
if(c=='\n')
{
a[i]='\0';
break;
}
else{
a[i]=c;
}
}
}
int operator(char o)
{
int r=0;
if(o=='+'||o=='-'||o=='*'||o=='/'||o=='$')
{
r=1;
}
return r;
}
int priority(char o)
{
int r;
switch(o)
{
case '(': r=0;
break;
case '+': r= 1;
break;
case '-': r= 1;
break;
case '*': r= 2;
break;
case '/': r= 2;
break;
case '$': r= 3;
}
return r;
}
int intopost(char a[],char out[])
{
int i=0,j=0;
while(a[i]!='\0')
{
if(operator(a[i]))
{
if(stackempty())
{
push(a[i]);
}
else
{
if(priority(a[i])>priority(stk[top]))
{
push(a[i]);
}
else
{
while(!stackempty() && priority(a[i])<=priority(stk[top]))
{
if (stk[top]!='('||stk[top]!='['||stk[top]!='{')
{
out[j] = pop();
j++;
}
else
{
printf("stk=%s",stk);
continue;
}
}
push(a[i]);
}
}
}
else if(a[i]=='('||a[i]=='['||a[i]=='{')
{
push(a[i]);
}
else if (a[i]==')'||a[i]==']'||a[i]=='}')
{
if(a[i]==')')
{
while (!stackempty() && stk[top] != '(')
{
out[j] = pop();
j++;
}
pop();
}
else if(a[i]==']')
{
while (!stackempty() && stk[top] != '[')
{
out[j] = pop();
j++;
}
pop();
}
else if(a[i]=='}')
{
while (!stackempty() && stk[top] != '{')
{
out[j] = pop();
j++;
}
pop();
}
}
else if((a[i]>='a'&&a[i]<='z')||(a[i]>='A'&&a[i]<='Z'))
{
out[j]=a[i];
j++;
}
i++;
}
printf("stk=%s",stk);
while(top!=-1)
{
out[j]=pop();
j++;
}
out[j]='\0';
j++;
}
int strlength(char a[])
{
int count=0,i;
for(i=0;i<50;i++)
{
if(a[i]!='\0')
{
count++;
}
else{
return count;
}
}
}
int main()
{
char s[70],o[70],ch;
int i,f;
printf("Enter the expression:");
getstr(s);
printf("%s -> ",s);
n=strlength(s);
intopost(s,o);
printf("%s",o);
}
Thanks to all for commenting suggestions!