Question

evaluating an expression using only one digit and + and - as operators ....3+5-1+7-5+8

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stack adt reading names and reversing them, remove vowels from the name and push it back into the stack

***please do both of those in c++*** I left it ambiguous so that you can fill in the blanks however you want

Answer 1

1.

CODE

// C++ program to evaluate a given expression

#include <iostream>

using namespace std;

// A utility function to check if a given character is operand

bool isOperand(char c) { return (c >= '0' && c <= '9'); }

// utility function to find value of and operand

int value(char c) { return (c - '0'); }

// This function evaluates simple expressions. It returns -1 if the

// given expression is invalid.

int evaluate(char *exp)

{

  // Base Case: Given expression is empty

  if (*exp == '\0') return -1;

  // The first character must be an operand, find its value

  int res = value(exp[0]);

  // Traverse the remaining characters in pairs

  for (int i = 1; exp[i]; i += 2)

  {

    // The next character must be an operator, and

    // next to next an operand

    char opr = exp[i], opd = exp[i+1];

    // If next to next character is not an operand

    if (!isOperand(opd)) return -1;

    // Update result according to the operator

    if (opr == '+') res += value(opd);

    else if (opr == '-') res -= value(opd);

    // If not a valid operator

    else         return -1;

  }

  return res;

}

// Driver program to test above function

int main()

{

  char expr1[] = "3+5-1+7-5+8";

  int res = evaluate(expr1);

  (res == -1)? cout << expr1 << " is " << "Invalid\n":

        cout << "Value of " << expr1 << " is " << res << endl;

  return 0;

}

OUTPUT

Value of 3+5-1+7-5+8 is 17

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