Mixed expressions, loops and Formatted output

Feb 22, 2015 at 9:37pm
map1987 (2)
Hello,

I need some general guidance with the following problem:

1) ask the user to input a mathematical expression in the following format:
NUMBER Operator NUMBER Operator NUMBER
Example: 17 + 15 - 3
Example: 2 * 3 - 4

I am having trouble figuring out how to output the answer of the users equation. Is there a function that includes all math operators (+,-,/,*)? Would i need to write each possible scenario using if statements?

Any help is greatly appreciated.
Feb 23, 2015 at 8:53am
coder777 (8449)
Is there a function that includes all math operators (+,-,/,*)?
No. Write your own. Four operators are not too many.

Would i need to write each possible scenario using if statements?
No. You might use switch. It's not that difficult:
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int do_operation(char op, int num1, int  num2)
{
  int result = 0;
  switch(op)
  {
  case '+':
  result = num1 + num2;
  break;
...
  }

  return result;
}
...
char op1, op2;
int num1, num2, num3;
...
cin >> num1 >> op1 >> num2 >> op2 >> num3;
cout << do_operation(op2, do_operation(op1, num1, num2), num3);
Feb 23, 2015 at 9:21am
billyb29 (44)
If that is all you doing (number operator number operator number) it won't be too long, and the code coder777 gave you works fine. Make sure you consider operator precedence too.
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