fork download
copy 
  1. %{ 
  2. #include <stdio.h> 
  3. #include <string.h> 
  4.     int operators_count = 0, operands_count = 0, valid = 1, top = -1, l = 0, j = 0; 
  5.     char operands[10][10], operators[10][10], stack[100]; 
  6. %} 
  7. %%
  8. "(" { 
  9.     top++; 
  10.     stack[top] = '('; 
  11. } 
  12. "{" {
  13.     top++; 
  14.     stack[top] = '{'; 
  15. } 
  16. "[" { 
  17.     top++; 
  18.     stack[top] = '['; 
  19. } 
  20. ")" { 
  21.     if (stack[top] != '(') { 
  22.         valid = 0;     
  23.     } 
  24.     else if(operands_count>0 && (operands_count-operators_count)!=1){
  25.         valid=0;
  26.     }
  27.     else{
  28.         top--;
  29.         operands_count=1;
  30.         operators_count=0;
  31.     } 
  32. } 
  33. "}" { 
  34.     if (stack[top] != '{') { 
  35.         valid = 0;     
  36.     } 
  37.     else if(operands_count>0 && (operands_count-operators_count)!=1){
  38.         valid=0;
  39.     }
  40.     else{
  41.         top--;
  42.         operands_count=1;
  43.         operators_count=0;
  44.     } 
  45. } 
  46. "]" { 
  47.     if (stack[top] != '[') { 
  48.         valid = 0; 
  49.     } 
  50.     else if(operands_count>0 && (operands_count-operators_count)!=1){
  51.         valid=0;
  52.     }
  53.     else{
  54.         top--;
  55.         operands_count=1;
  56.         operators_count=0;
  57.     } 
  58.  
  59. } 
  60. "+"|"-"|"*"|"/" { 
  61.     operators_count++; 
  62.     strcpy(operators[l], yytext); 
  63.     l++; 
  64. } 
  65. [0-9]+|[a-zA-Z][a-zA-Z0-9_]* { 
  66.     operands_count++; 
  67.     strcpy(operands[j], yytext); 
  68.     j++; 
  69. } 
  70. %% 
  71.  
  72.  
  73. int yywrap() 
  74. { 
  75.     return 1; 
  76. } 
  77. int main() 
  78. { 
  79.     int k; 
  80.     printf("Enter the arithmetic expression: "); 
  81.     yylex(); 
  82.  
  83.     if (valid == 1 && top == -1) { 
  84.         printf("\nValid Expression\n"); 
  85.     } 
  86.     else
  87.         printf("\nInvalid Expression\n"); 
  88.  
  89.     return 0;
  90. }
Success #stdin #stdout #stderr 0.02s 6844KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
Standard output is empty
stderr
copy 
ERROR: /home/bkqHXU/prog:90:1: Syntax error: Unexpected end of file
ERROR: '$runtoplevel'/0: Undefined procedure: program/0
   Exception: (3) program ? EOF: exit
https://ideone.com/ak2UTM
language:
Prolog (swi 7.6.4)
created:
1 year ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!