Create Postfix evaluation.c

DSA/Postfix evaluation.c

@@ -0,0 +1,104 @@
+#include<stdio.h>
+#include<stdlib.h>
+#include<string.h>
+#include<math.h>
+
+#define max 50
+#define blank ' '
+#define tab '\t'
+
+char postfix[max];
+float eval[max];
+int top=-1;
+
+int eval_isfull()
+{
+if(top==(max-1))
+return 1;
+return 0;
+}
+
+int eval_isempty()
+{
+if(top==-1)
+return 1;
+return 0;
+}
+
+float eval_pop()
+{
+if(eval_isempty())
+{
+printf("\nStack is empty.Pop operation can't be performed");
+return -1;
+}
+return eval[top--];
+}
+
+void eval_push(float n)
+{
+if(eval_isfull())
+{
+printf("\nStack is full.Push operation can't be performed");
+return;
+}
+eval[++top]=n;
+}
+float post_eval(char postfix[])
+{
+float a,b;
+int i,j;
+
+float item;
+char symbol;
+for(i=0;postfix[i]!='\0';i++)
+{
+symbol=postfix[i];
+switch(symbol)
+{
+case '^':
+case '$':
+a=eval_pop();
+b=eval_pop();
+eval_push(pow(b,a));
+break;
+case '*':
+a=eval_pop();
+b=eval_pop();
+eval_push(b*a);
+break;
+case '/':
+a=eval_pop();
+b=eval_pop();
+eval_push((b/a));
+break;
+case '%':
+a=eval_pop();
+b=eval_pop();
+eval_push(((int)b%(int)a));
+break;
+case '+':
+a=eval_pop();
+b=eval_pop();
+eval_push((b+a));
+break;
+case '-':
+a=eval_pop();
+b=eval_pop();
+eval_push((b-a));
+break;
+default:
+printf("\nEnter the value of %c :",postfix[i]);
+scanf("%f",&item);
+eval_push(item);
+}
+}
+return *eval;
+}
+int main()
+{
+printf("\nEnter the Postfix expression :\n");
+scanf("\n%[^\n]%*c",postfix);
+printf("\nResult = %.2f",post_eval(postfix));
+return 0;
+}