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/***************************************************
A Very Simple Calculator

Write a program that reads from the user a simple
arithmetic expression using + and -, like

     3 + 4 - 7 + 2 - 4 =

and prints out the value of the expression.
***************************************************/
#include "si204.h"

int main() {
  fputs("Enter an expression: ", stdout);

  // declare variables and do the loop initialization
  int total;
  int nextnum;
  char nextop;
  total = 0;
  nextop = '+';

  // keep adding/subtracting until we see an = sign
  while (nextop != '=') {
    nextnum = readnum(stdin);

    if (nextop == '+') {
      total = total + nextnum;
    } else {
      total = total - nextnum;
    }

    nextop = readchar(stdin);
  }

  // Write result
  fputs("The total is: ", stdout);
  writenum(total, stdout);
  fputs("\n", stdout);

  return 0;
}