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allenjiji · Oct 26, 2019 · 4a31513 · 4a31513
1 parent 7b6e265
commit 4a31513
Showing 1 changed file with 101 additions and 0 deletions.
diff --git a/postfix.c b/postfix.c
@@ -0,0  1,101 @@
 #include<stdio.h>
 #include<stdlib.h>
 #include<ctype.h>
 #define MAX 25
 char a[MAX],b[MAX],stack[MAX];
 int top=-1;
 
 void push(char c){
   if(top>MAX){
     printf("An Error Occured! Please update MAX for better Perfomance.\n");
     exit(0);
   }
   else{
     top  ;
     stack[top]=c;
   }
 }
 
 char pop(){
   if(top==-1) {
     printf("An Error Occured!\n");
     exit(0);
   }
   else{
     char a=stack[top];
     top--;
     return a;
   }
 }
 
 
 
 void display(){
   for(int i=0;b[i]!='\0';i  ){
     printf("%c",b[i]);
   }
 }
 
 void insert(){
   scanf("%s",a);
 }
 
 int priority(char c){
   if(c==' ' ||c=='-') return 1;
   else if(c=='*' ||c=='/') return 2;
   else if(c=='^') return 3;
   else if(c=='(') return 0;
 }
 
 int isoperator(char x){
   if(x=='*'||x=='^'||x=='/'||x=='-'||x==' ') return 1;
   else return 0;
 }
 
 
 
 void convert(){
   push('(');
   int i;
   for (i=0;a[i]!='\0';i  );
   a[i  ]=')';
   a[i]='\0';
   int j=0;
   for (i=0;a[i]!='\0';i  ){
     if(isalpha(a[i])){
       b[j  ]=a[i];
     }
 
 
     else if(a[i]=='(') push(a[i]);
 
     else if(a[i]==')'){
       while(stack[top]!='('){
         b[j  ]=pop();
       }
       char z=pop();
     }
     else if(isoperator(a[i])){
       char c=a[i];
       char d=stack[top];
       while(priority(c)<=priority(d)){
         b[j  ]=pop();
       }
       push(c);
     }
   }
   b[j]='\0';
 }
 
 
 
 void main(){
   while(1){
   printf("Enter the infix expression:");
   insert();
   convert();
   printf("The postfix expression is:");
   display();
   printf("\n");
 }
 }