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  1. #include <stdio.h>
  2. #include <ctype.h>
  3.  
  4. void
  5. push(char *s, int *top, int c)
  6. {
  7.     s[*top] = c;
  8.     (*top)++;
  9. }
  10.  
  11. int
  12. pop(char *s, int *top)
  13. {
  14.     (*top)--;
  15.     return s[*top];
  16. }
  17.  
  18. void
  19. infix_to_postfix(char *in, char *post, char *stk, int *tp, int *ts)
  20. {
  21.     char operator[256] = {0};
  22.  
  23.     operator['('] = 0;
  24.     operator['+'] = 1;
  25.     operator['-'] = 1;
  26.     operator['*'] = 2;
  27.     operator['/'] = 2;
  28. /* This program stop here */
  29.     while (*in) {
  30.         if (isdigit(*in)) {
  31.             push(post, tp, *in); /*! push_p() */
  32.         } else { /* Operator */
  33.             while (1) {
  34.                 switch (*in) {
  35.                     case '(':
  36.                         push(stk, ts, *in); /*! push_s() */
  37.                         break;
  38.                     case ')':
  39.                         while (stk[*ts - 1] != '(') {
  40.                             push(post, tp, pop(stk, ts)); /*! push_p( pop_s() ) */
  41.                         }
  42.                         pop(stk, ts); /*! pop_s() */
  43.                         break;
  44.                     default:
  45.                         break;
  46.                 }
  47.                 if (*in == '(' && *in == ')') {
  48.                     break;
  49.                 }
  50.                 if (!stk[*ts - 1]) {
  51.                     while (operator[stk[*ts - 1]] >= operator[*in]) {
  52.                         push(post, tp, pop(stk, ts));	/*! push_p( pop_s() ) */
  53.                         if (stk[*ts - 1]) {
  54.                             break;
  55.                         }
  56.                     }
  57.                 }
  58.                 break;
  59.             }
  60.             if (*in != '(' && *in != ')') {
  61.                 push(stk, ts, *in);	/* !push_s() */
  62.             }
  63.         }
  64.         in++;
  65.     }
  66. }
  67.  
  68. void
  69. stack_empty(char *post, char *stk, int *ts, int *tp)
  70. {
  71.     while (stk[*ts - 1]) {
  72.         push(post, tp, pop(stk, ts));	/*! push_p( pop_s() ) */
  73.     }
  74. }
  75.  
  76. int
  77. main(int argc, char **argv)
  78. {
  79.     char infix[] = "2*((3-5)*2)";
  80.     char postfix[256] = {0};
  81.     char stack[256] = {0};
  82.     int top_p = 0;
  83.     int top_s = 0;
  84.  
  85. 	infix_to_postfix(infix, postfix, stack, &top_p, &top_s);
  86. 	stack_empty(postfix, stack, &top_p, &top_s);
  87.     printf("%s\n", postfix);
  88.     return 0;
  89. }
  90.  
Success #stdin #stdout 0s 2248KB
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stdin
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Standard input is empty
stdout
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235-2*
https://ideone.com/QBPqKE
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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