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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <ctype.h>
  4.  
  5. char input[100], stack[100];
  6. int top = -1;
  7.  
  8. void push(char c) {
  9.     stack[++top] = c;
  10.     stack[top + 1] = '\0';
  11. }
  12.  
  13. void reduce() {
  14.     // E -> id
  15.     if (top >= 0 && isalpha(stack[top])) {
  16.         stack[top] = 'E';
  17.         printf("Reduce: E -> id\n");
  18.     }
  19.  
  20.     // E -> (E)
  21.     if (top >= 2 && stack[top] == ')' && stack[top - 1] == 'E' && stack[top - 2] == '(') {
  22.         stack[top - 2] = 'E';
  23.         top -= 2;
  24.         stack[top + 1] = '\0';
  25.         printf("Reduce: E -> (E)\n");
  26.     }
  27.  
  28.     // E -> E + E
  29.     if (top >= 2 && stack[top] == 'E' && stack[top - 1] == '+' && stack[top - 2] == 'E') {
  30.         stack[top - 2] = 'E';
  31.         top -= 2;
  32.         stack[top + 1] = '\0';
  33.         printf("Reduce: E -> E + E\n");
  34.     }
  35.  
  36.     // E -> E * E
  37.     if (top >= 2 && stack[top] == 'E' && stack[top - 1] == '*' && stack[top - 2] == 'E') {
  38.         stack[top - 2] = 'E';
  39.         top -= 2;
  40.         stack[top + 1] = '\0';
  41.         printf("Reduce: E -> E * E\n");
  42.     }
  43. }
  44.  
  45. int main() {
  46.     printf("Enter Expression: ");
  47.  
  48.     scanf(" %[^\n]", input); // بدل fgets
  49.  
  50.     for (int i = 0; input[i] != '\0'; i++) {
  51.  
  52.         if (input[i] == ' ')
  53.             continue;
  54.  
  55.         push(input[i]);
  56.         printf("Shift: %s\n", stack);
  57.  
  58.         reduce();
  59.     }
  60.  
  61.     if (strcmp(stack, "E") == 0)
  62.         printf("String Accepted\n");
  63.     else
  64.         printf("String Rejected\n");
  65.  
  66.     return 0;
  67. }
Success #stdin #stdout 0s 5320KB
comments (?)
stdin
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(a + (b*a))
stdout
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Enter Expression: Shift: (
Shift: (a
Reduce: E -> id
Shift: (E+
Shift: (E+(
Shift: (E+(b
Reduce: E -> id
Shift: (E+(E*
Shift: (E+(E*a
Reduce: E -> id
Reduce: E -> E * E
Shift: (E+(E)
Reduce: E -> (E)
Reduce: E -> E + E
Shift: (E)
Reduce: E -> (E)
String Accepted
https://ideone.com/W0yn0q
language:
C (gcc 8.3)
created:
15 hours ago
visibility:
public

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