Question

prefix of (a+b)*(c-d) is​

Answer 1

Answer:

Prefix of (a+b)*(c-d) is​     * + ab - cd

Explanation:

• The 'Pre' refers to the relative position of the operator with respect to the two operands.
• In prefix notation the operator precedes the two operands.
• conversion of (a+b)*(c-d) to its prefix notation is as follows:

Step 1 :   (+ab)*(-cd)

Step 2 : *(+ab)(-cd)

The prefix form of an expression requires no parenthesis.

Hence *(+ab)(-cd) should be written as * + ab - cd

Answer 2

Answer:

Prefix expression is given by $*+AB-CD$

Explanation:

Given: An infix expression

Find: Conversion from infix to prefix expression

Step1:

Infix :

• An expression is called the Infix expression if the operator appears in between the operands in the expression.
• Simply of the form (operand1 operator operand2).
• Example : $(A+B) * (C-D)$

Prefix:

• An expression is called the prefix expression if the operator appears in the expression before the operands.
• Simply of the form (operator operand1 operand2).e.g. $*+AB-CD$

Conversion step for infix to prefix expression

• To convert Infix to Prefix expression, computers usually use the stack data structure.
• Reverse the infix expression.
• Obtain the “nearly” postfix expression of the modified expression.
• Reverse the postfix expression.
• Push “)” onto STACK, and add “(“ to the end of the A
• Scan A from right to left and repeat steps 3 to 6 for each element of A until the STACK is empty
• If an operand is encountered add it to B
• If a right parenthesis is encountered push it onto STACK
• If an operator is encountered then:
• a. Repeatedly pop from STACK and add to B each operator (on the top of STACK) which has the same or higher precedence than the operator.
• b. Add operator to STACK
• If left parenthesis is encountered then
• a. Repeatedly pop from the STACK and add to B (each operator on top of stack until a left parenthesis is encountered)
• b. Remove the left parenthesis
• Exit