Infix to Postfix Conversion Using Stack in DSA C - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a character is an operator.

DSA C

int isOperator(char c) {
    return (c == '+' || c == '-' || c == '*' || c == [1]);
}

Drag options to blanks, or click blank then click option'

A/

B%

C^

D&

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-operator symbol like '&' or '%'.

Forgetting to include '/' as an operator.

The division operator '/' is a common operator in infix expressions and must be checked.

2fill in blank

medium

Complete the code to return precedence of operators.

DSA C

int precedence(char op) {
    if (op == '+' || op == '-')
        return 1;
    if (op == '*' || op == [1])
        return 2;
    return 0;
}

Drag options to blanks, or click blank then click option'

A-

B/

C^

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' or '-' which have lower precedence.

Using '^' which is not handled here.

Division '/' has the same precedence as multiplication '*', so it should return 2.

3fill in blank

hard

Fix the error in the stack push function to correctly add an element.

DSA C

void push(char stack[], int *top, char value) {
    stack[++[1]] = value;
}

Drag options to blanks, or click blank then click option'

A*top

Btop

C&top

D(*top)

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'top' directly increments the pointer, not the value.

Using '&top' is incorrect as it gives address of pointer.

We must increment the value pointed by top, so ++*top is correct.

4fill in blank

hard

Fill in the blank to correctly pop an element from the stack.

DSA C

char pop(char stack[], int *top) {
    return stack[[1]--];
}

Drag options to blanks, or click blank then click option'

A*top

Btop

C(*top)

D&top

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'top' without dereferencing causes errors.

Using '&top' is incorrect as it is address of pointer.

(*top)-- correctly returns the top element and then decrements the top index.

5fill in blank

hard

Fill both blanks to correctly convert infix to postfix expression.

DSA C

void infixToPostfix(char* infix, char* postfix) {
    char stack[100];
    int top = -1, i = 0, k = 0;
    while (infix[i] != '\0') {
        char c = infix[i];
        if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) {
            postfix[k++] = c;
        } else if (c == '(') {
            stack[++top] = c;
        } else if (c == ')') {
            while (top != -1 && stack[top] != () {
                postfix[k++] = stack[top--];
            }
            top--;
        } else if (isOperator(c)) {
            while (top != -1 && precedence(stack[top]) >= [1]) {
                postfix[k++] = stack[top--];
            }
            stack[++top] = [2];
        }
        i++;
    }
    while (top != -1) {
        postfix[k++] = stack[top--];
    }
    postfix[k] = '\0';
}

Drag options to blanks, or click blank then click option'

A(

Bc

Ctop

Dprecedence(c)

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong character for '(' in popping loop.

Comparing precedence with stack top instead of current operator.

Pushing wrong character onto stack.

When encountering ')', pop until '(' is found (blank 1 = '(').The operator to push is c (blank 3 = c).