Evaluation_of_postfix_using_stack.c

Evaluation_of_postfix_using_stack.c

@@ -0,0 +1,78 @@
+/*Evaluation of postfix expression in c*/
+#include<stdio.h>
+#include<math.h>
+#include<string.h>
+#include<stdlib.h>
+#include<ctype.h>
+int stack[20];
+int top = -1;
+
+void push(int x)
+{
+    stack[++top] = x;
+}
+
+int pop()
+{
+    return stack[top--];
+}
+
+int main()
+{
+    char exp[20];
+    char *e;
+    int n1,n2,n3,num;
+    scanf("%s",exp);
+    e = exp;
+    while(*e != '\0')
+    {
+        if(isdigit(*e))
+        {
+            num = *e - 48;
+            push(num);
+        }
+        else
+        {
+            n1 = pop();
+            n2 = pop();
+            switch(*e)
+            {
+            case '+':
+            {
+                n3 = n1 + n2;
+                break;
+            }
+            case '-':
+            {
+                n3 = n2 - n1;
+                break;
+            }
+            case '*':
+            {
+                n3 = n1 * n2;
+                break;
+            }
+            case '/':
+            {
+                n3 = n2 / n1;
+                break;
+            }
+            case '^':
+            {
+                n3 = pow(n2,n1);
+                break;
+            }
+            }
+            push(n3);
+        }
+        e++;
+    }
+    printf("%d\n\n",pop());
+    return 0;
+}
+
+/*Test case
+Input
+6523+8*+3+*
+Expected output
+288