A complete code block example on Postfix Evaluation in C Data Structures.
The following code snippet is complete working C-code on evaluating postfix. I have commented the code for easy understanding.
- Size of Stack
- Global declarations
- Read the postfix expressions
- Push the operand
- Operator/pop two operands
- Invalid Operator
- Printing the given postfix operations
- The result after evaluation.
/* Evaluating postfix */ #include <stdio.h> #include <math.h> #define SIZE 50 /* Size of Stack */ #include <ctype.h> int s[SIZE]; int top=-1; /* Global declarations */ push(int elem) { s[++top]=elem; } int pop() { return(s[top--]); } main() { char pofx[50],ch; int i=0,op1,op2; printf("\n\nRead the Postfix Expression ? "); scanf("%s",pofx); while( (ch=pofx[i++]) != '\0') { if(isdigit(ch)) push(ch-'0'); /* Push the operand */ else { /* Operator,pop two operands */ op2=pop(); op1=pop(); switch(ch) { case '+':push(op1+op2);break; case '-':push(op1-op2);break; case '*':push(op1*op2);break; case '/':push(op1/op2);break; case '%':push(op1%op2);break; case '^':push(pow(op1,op2));break; default : printf("Invalid operator\n"); } } } printf("\n Given Postfix Expn: %s\n",pofx); printf("\n Result after Evaluation: %d\n",s[top]); }
Conclusion
The Data Structure code will help to print the user-provided expression and gives the result after Postfix Evaluation in C programming language.