Evaluating Postfix Expression

 Evaluating Postfix Expression

CODE

👇

1. #include <stdio.h>
2. #include <ctype.h>
3. #define MAX 20
4. typedef struct
5. {
6. int data[MAX];
7. int top;
8. }STACK;
9. 
   
10. void initstack(STACK *ps)
11. {
12. ps->top = -1;
13. }
14. 
    
15. void push(STACK *ps, int num)
16. {
17. ps->top++;
18. ps->data[ps->top]=num;
19. }
20. 
    
21. int pop(STACK *ps)
22. {
23. return(ps->data[ps->top--]);
24. }
25. 
    
26. int isempty(STACK *ps)
27. {
28. return(ps->top == -1);
29. }
30. 
    
31. int isfull(STACK *ps)
32. {
33. return(ps->top == MAX-1);
34. }
35. 
    
36. void main()
37. {
38. void Eval(char post[]);
39. char post[20];
40. printf(">>Evaluating Postfix Expression<<\n");
41. printf("Enter The Postfix Expression:\t");
42. scanf("%s", post);
43. Eval(post);
44. }
45. 
    
46. void Eval(char post[])
47. {
48. int value, i, op1, op2;
49. STACK s1;
50. initstack(&s1);
51. for(i=0; post[i]!='\0'; i++)
52. {
53. if(isalpha(post[i]))
54. {
55. printf("Enter The Value Of %c: \t", post[i]);
56. scanf("%d", &value);
57. push(&s1, value);
58. }
59. else
60. {
61. op2=pop(&s1);
62. op1=pop(&s1);
63. switch(post[i])
64. {
65. case '+':
66. push(&s1, op1+op2);
67. break;
69. case '-':
70. push(&s1, op1-op2);
71. break;
73. case '*':
74. push(&s1, op1*op2);
75. break;
77. case '/':
78. push(&s1, op1/op2);
79. break;
81. case '%':
82. push(&s1, op1%op2);
83. break;
85. default:
86. printf("Enter Value The Value Of");
87. scanf("%d", &value);
88. push(&s1, value);
89. break;
90. }
91. }
92. }
93. printf("The Result Is: %d \n", pop(&s1));
94. }

👉Execute👈

//OUTPUT

/*

>>Evaluating Postfix Expression<<

Enter The Postfix Expression:   ABC*+DE/-

Enter The Value Of A:   78

Enter The Value Of B:   14

Enter The Value Of C:   64

Enter The Value Of D:   52

Enter The Value Of E:   43

The Result Is: 973

*/

                                        //ThE ProFessoR