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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #define SIZE  100   
  5. int count=0;        
  6. typedef struct node{
  7.  char value;
  8.  struct stack *next;
  9.  struct stack *prev;
  10. }stack;
  11.  
  12. stack *bottom=NULL;
  13. stack *top=NULL;
  14.  
  15. stack *createnode(char a)
  16. {
  17.  stack *newstack;
  18.  newstack=(stack*)calloc(1,sizeof(stack));
  19.  newstack->value=a;
  20.  newstack->prev=NULL;
  21.  newstack->next=NULL;
  22.  return newstack;
  23. }
  24.  
  25. int isempty()
  26.    {
  27.        if(count==0)
  28.        {return 1;}
  29.        else
  30.        {return 0;}
  31.     }
  32.  
  33. int isfull()
  34.     {
  35.      if(count==SIZE)
  36.      {return 1;}
  37.      else
  38.      {return 0;}
  39.     }
  40.  
  41. void push(char a) 
  42. {   if(isfull()==1) 
  43.    {
  44.     printf("overflow condition: stack full");
  45.    }
  46.  else               
  47.    {count+=1;       
  48.  stack *newstack = createnode(a);
  49.  if(bottom==NULL)   
  50.  {
  51.  bottom=newstack;
  52.  top=bottom;
  53.  }
  54.  else               
  55.  {
  56.   top->next=newstack;
  57.   newstack->prev=top;
  58.   top=newstack;
  59.  }
  60.    } 
  61. }
  62. char peek()         
  63. { 
  64.    	return top->value;
  65. }
  66. char pop()        
  67.     {   if(isempty()==1)          
  68.         {
  69.          printf("underflow condition:empty stack");
  70.         }
  71.         else 
  72.         {if(count==1)             
  73.         {   char c;
  74.          c=top->value;
  75.          top=NULL;
  76.          bottom=NULL;
  77.          count=count-1;
  78.          return c;
  79.  
  80.         }
  81.         else                           
  82.      {char c;
  83.      c=top->value;
  84.   top=top->prev;
  85.   top->next=NULL;
  86.   count=count-1;
  87.   return c;
  88.  
  89.      }
  90.        } 
  91.     }
  92.     char plus=43;
  93.     char multi=42;
  94.     char divi=47;
  95.     char power=94;
  96.     char left=40;
  97.     char right=41;
  98.     char subtract=45;
  99. int precedence(char c)
  100. {  int precide=0;
  101. 	if(c==subtract)
  102. 	{precide+=0;}
  103. 	if(c==plus)
  104. 	{precide+=1;}
  105. 	if(c==multi)
  106. 	{precide+=2;}
  107. 	if(c==divi)
  108. 	{precide+=3;}
  109. 	if(c==power)
  110. 	{precide+=4;}
  111. 	if(c==left || c==right)
  112. 	{precide+=5;}
  113. 	return precide;
  114. 	precide=0;
  115. }
  116.  
  117. char *postfix_converter(char *string,int length)
  118. { char s[100]="\0"; int i; stack operators;
  119. 	for(i=0;i<length;i++)
  120. 	{   
  121. 		char c; 
  122. 		c=string[i];
  123. 		if(c==plus || c==subtract || c==multi || c==divi || c==power || c==left)
  124. 		{
  125. 		  if(top==NULL)
  126. 		  {
  127. 		  	push(c);
  128. 		  }
  129. 		  else
  130. 		  {
  131. 		  	if(precedence(c)>precedence(peek()) || peek()==left)
  132. 		  	{
  133. 		  		push(c);
  134. 		  	}
  135. 		  	else
  136. 		  	{  
  137. 		  		char r[2]="\0";
  138. 		  	    r[0]=pop();
  139. 		  	    strcat(s,r);
  140. 		  	    push(c);
  141. 		  	}
  142.  
  143. 		  }
  144. 		}
  145. 		else
  146. 		{
  147. 			if(c==right)
  148. 			{
  149. 			 while(peek()!=left)
  150. 			 {
  151. 			    char r[2]="\0";
  152. 		  	    r[0]=pop();
  153. 		  	    strcat(s,r);
  154. 			 }
  155. 			 pop();
  156. 			}
  157. 			else
  158. 			{
  159. 			    char r[2]="\0";
  160. 		  	    r[0]=c;
  161. 		  	    strcat(s,r);
  162. 		  	 //  printf("%s\n",s);
  163. 		  	//  char j=peek();
  164. 		  	//  printf("%c",j);
  165.  
  166. 			}
  167. 		}
  168. 		if(i==(length-1))
  169. 		{// printf("%d",count);
  170. 		  while(count>0)
  171. 		  {
  172. 		  	 char r[2]="\0";
  173. 		  	    r[0]=pop();
  174. 		  	    strcat(s,r);
  175. 		 // 	    printf("lool");
  176. 		  }
  177. 		}
  178.  
  179. 		//	printf("%d\n",count);
  180. 		//	printf("%s\n",s);
  181.   	}
  182.  
  183. 	//printf("%d\n",pop());
  184.    printf("%s",s);
  185. }
  186.  
  187. // driver code , the main function
  188.  
  189. int main(void)
  190. {   char inversion[200]; 
  191. 	printf("give the infix expression\n");
  192. 	scanf("%s",&inversion);
  193. 	int longer=strlen(inversion);
  194. 	postfix_converter(inversion,longer);
  195.  
  196. 	return 0;
  197. }
Success #stdin #stdout 0s 9432KB
comments (?)
stdin 
(3/3)^3+3-3
stdout 
give the infix expression
33/3^3+3-
https://ideone.com/0zPvtb
language:
C (gcc 8.3)
created:
5 years ago
visibility:
public

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