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  1. #include <stdio.h>
  2. #include <string.h>
  3. #include <ctype.h>
  4.  
  5. char stack[100][10];
  6. int top = -1;
  7. int pos = 0;
  8. char input[100];
  9.  
  10. void push(const char *s) {
  11.     strcpy(stack[++top], s);
  12. }
  13.  
  14. void pop() {
  15.     top--;
  16. }
  17.  
  18. void printStack() {
  19.     for (int i = 0; i <= top; i++)
  20.         printf("%s", stack[i]);
  21.     printf("\n");
  22. }
  23.  
  24. int reduce(char lookahead) {
  25.  
  26.     // F -> id
  27.     if (top >= 0 &&
  28.         stack[top][0] >= 'a' &&
  29.         stack[top][0] <= 'z')
  30.     {
  31.         pop();
  32.         push("F");
  33.         return 1;
  34.     }
  35.  
  36.     // F -> (E)
  37.     if (top >= 2 &&
  38.         strcmp(stack[top-2], "(") == 0 &&
  39.         strcmp(stack[top-1], "E") == 0 &&
  40.         strcmp(stack[top], ")") == 0)
  41.     {
  42.         pop(); pop(); pop();
  43.         push("F");
  44.         return 1;
  45.     }
  46.  
  47.     // T -> T * F
  48.     if (top >= 2 &&
  49.         strcmp(stack[top-2], "T") == 0 &&
  50.         strcmp(stack[top-1], "*") == 0 &&
  51.         strcmp(stack[top], "F") == 0)
  52.     {
  53.         pop(); pop(); pop();
  54.         push("T");
  55.         return 1;
  56.     }
  57.  
  58.     // T -> F
  59.     if (top >= 0 && strcmp(stack[top], "F") == 0)
  60.     {
  61.         pop();
  62.         push("T");
  63.         return 1;
  64.     }
  65.  
  66.     // E -> E + T  (مع مراعاة precedence)
  67.     if (top >= 2 &&
  68.         strcmp(stack[top-2], "E") == 0 &&
  69.         strcmp(stack[top-1], "+") == 0 &&
  70.         strcmp(stack[top], "T") == 0)
  71.     {
  72.         // لو الجاي * نستنى
  73.         if (lookahead == '*')
  74.             return 0;
  75.  
  76.         pop(); pop(); pop();
  77.         push("E");
  78.         return 1;
  79.     }
  80.  
  81.     // E -> T (مع مراعاة precedence)
  82.     if (top >= 0 && strcmp(stack[top], "T") == 0)
  83.     {
  84.         // لو الجاي * يبقى لسه هنكوّن T * F
  85.         if (lookahead == '*')
  86.             return 0;
  87.  
  88.         pop();
  89.         push("E");
  90.         return 1;
  91.     }
  92.  
  93.     return 0;
  94. }
  95.  
  96. int main() {
  97.     printf("Enter an Expression:\n");
  98.     fgets(input, 100, stdin);
  99.  
  100.     while (input[pos]) {
  101.  
  102.         if (isspace(input[pos])) {
  103.             pos++;
  104.             continue;
  105.         }
  106.  
  107.         char temp[2] = {input[pos], '\0'};
  108.         push(temp);
  109.         pos++;
  110.  
  111.         printf("Shift: ");
  112.         printStack();
  113.  
  114.         while (reduce(input[pos])) {
  115.             printf("Reduce: ");
  116.             printStack();
  117.         }
  118.     }
  119.  
  120.     while (reduce('\0')) {
  121.         printf("Reduce: ");
  122.         printStack();
  123.     }
  124.  
  125.     if (top == 0 && strcmp(stack[0], "E") == 0)
  126.         printf("String Accepted\n");
  127.     else
  128.         printf("String Rejected\n");
  129.  
  130.     return 0;
  131. }
Success #stdin #stdout 0s 5320KB
comments (?)
stdin
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Standard input is empty
stdout
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Enter an Expression:
String Rejected
https://ideone.com/O0yViy
Task Compilers
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

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