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  1. #include <stdio.h>
  2. #include <ctype.h>
  3. #include <stdlib.h>
  4. #include <string.h>
  5.  
  6. char input[100];  // Input buffer
  7. int pos = 0;      // Current position in input
  8. char token;       // Current character (token)
  9. int tempCount = 0; // Temporary variable counter
  10.  
  11. // Function to get next token
  12. void getToken() {
  13.     while (input[pos] == ' ' || input[pos] == '\t') pos++;
  14.     token = input[pos++];
  15. }
  16.  
  17. // Function to create new temporary variable name
  18. char* newTemp() {
  19.     static char temp[10];
  20.     sprintf(temp, "t%d", tempCount++);
  21.     return strdup(temp);
  22. }
  23.  
  24. // Forward declarations
  25. char* expression();
  26.  
  27. // Function to handle numbers or identifiers
  28. char* factor() {
  29.     char* result = (char*)malloc(10);
  30.     if (isdigit(token)) {
  31.         sprintf(result, "%c", token);
  32.         getToken();
  33.     } else if (isalpha(token)) {
  34.         sprintf(result, "%c", token);
  35.         getToken();
  36.     } else {
  37.         printf("Syntax Error in factor!\n");
  38.         exit(1);
  39.     }
  40.     return result;
  41. }
  42.  
  43. // Function to handle multiplication and division
  44. char* term() {
  45.     char* left = factor();
  46.     while (token == '*' || token == '/') {
  47.         char op = token;
  48.         getToken();
  49.         char* right = factor();
  50.         char* temp = newTemp();
  51.         printf("%s = %s %c %s\n", temp, left, op, right);
  52.         left = temp;
  53.     }
  54.     return left;
  55. }
  56.  
  57. // Function to handle addition and subtraction
  58. char* expression() {
  59.     char* left = term();
  60.     while (token == '+' || token == '-') {
  61.         char op = token;
  62.         getToken();
  63.         char* right = term();
  64.         char* temp = newTemp();
  65.         printf("%s = %s %c %s\n", temp, left, op, right);
  66.         left = temp;
  67.     }
  68.     return left;
  69. }
  70.  
  71. // Function to handle the assignment statement
  72. void assignment() {
  73.     if (!isalpha(token)) {
  74.         printf("Syntax Error: Expected identifier on the left-hand side\n");
  75.         exit(1);
  76.     }
  77.  
  78.     char id = token;
  79.     getToken();
  80.  
  81.     if (token != '=') {
  82.         printf("Syntax Error: Expected '=' after identifier\n");
  83.         exit(1);
  84.     }
  85.  
  86.     getToken(); // Skip '='
  87.     char* result = expression();
  88.  
  89.     if (token != ';') {
  90.         printf("Syntax Error: Expected ';' at the end\n");
  91.         exit(1);
  92.     }
  93.  
  94.     printf("%c = %s\n", id, result);
  95. }
  96.  
  97. int main() {
  98.     printf("Enter an expression (e.g., a = 3 + 4 * b;): ");
  99.     fgets(input, sizeof(input), stdin);
  100.  
  101.     getToken();
  102.     assignment();
  103.  
  104.     return 0;
  105. }
Success #stdin #stdout #stderr 0.03s 6960KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
stderr 
ERROR: /home/o4gDxI/prog:105:0: Syntax error: end_of_file_in_quasi_quotation
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/o8aH0D
language:
Prolog (swi 7.6.4)
created:
12 days ago
visibility:
public

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