Sure, here is a Python program that evaluates postfix expressions using a stack:

```python
def evaluate_postfix(expression):
stack = []
for char in expression:
if char.isdigit():
stack.append(int(char))
else:
operand2 = stack.pop()
operand1 = stack.pop()
if char == '+':
stack.append(operand1 + operand2)
elif char == '-':
stack.append(operand1 - operand2)
elif char == '*':
stack.append(operand1 * operand2)
elif char == '/':
stack.append(operand1 / operand2)
return stack[0]

# Test the function
print(evaluate_postfix('82/')) # Output: 4
print(evaluate_postfix('545*+5/')) # Output: 5
print(evaluate_postfix('82-4+')) # Output: 10
```

This program works by iterating over each character in the expression. If the character is a digit, it is pushed onto the stack. If the character is an operator, the top two elements are popped from the stack, the operation is performed, and the result is pushed back onto the stack. At the end of the expression, the only element left on the stack is the result.

Question

Sure, here is a Python program that evaluates postfix expressions using a stack:

```python
def evaluate_postfix(expression):
    stack = []
    for char in expression:
        if char.isdigit():
            stack.append(int(char))
        else:
            operand2 = stack.pop()
            operand1 = stack.pop()
            if char == '+':
                stack.append(operand1 + operand2)
            elif char == '-':
                stack.append(operand1 - operand2)
            elif char == '*':
                stack.append(operand1 * operand2)
            elif char == '/':
                stack.append(operand1 / operand2)
    return stack[0]

# Test the function
print(evaluate_postfix('82/'))  # Output: 4
print(evaluate_postfix('545*+5/'))  # Output: 5
print(evaluate_postfix('82-4+'))  # Output: 10
```

This program works by iterating over each character in the expression. If the character is a digit, it is pushed onto the stack. If the character is an operator, the top two elements are popped from the stack, the operation is performed, and the result is pushed back onto the stack. At the end of the expression, the only element left on the stack is the result.

Knowee AI · Accepted Answer

Sure, here is a Python program that evaluates postfix expressions using a stack:

```python
def evaluate_postfix(expression):
    stack = []
    for char in expression:
        if char.isdigit():
            stack.append(int(char))
        else:
            operand2 = stack.pop()
            operand1 = stack.pop()
            if char == '+':
                stack.append(operand1 + operand2)
            elif char == '-':
                stack.append(operand1 - operand2)
            elif char == '*':
                stack.append(operand1 * operand2)
            elif char == '/':
                stack.append(operand1 / operand2)
    return stack[0]

# Test the function
print(evaluate_postfix('82/'))  # Output: 4
print(evaluate_postfix('545*+5/'))  # Output: 5
print(evaluate_postfix('82-4+'))  # Output: 10
```

This program works by iterating over each character in the expression. If the character is a digit, it is pushed onto the stack. If the character is an operator, the top two elements are popped from the stack, the operation is performed, and the result is pushed back onto the stack. At the end of the expression, the only element left on the stack is the result.

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