C++ proggie syntax problem

Hi there,

I am reading and entering the code from O'Reilly's Practical C++ Programming book. my g++ is complaining of syntax errors in example 7-1 from chapter 1. Might somebody explain why I am getting these errors.

Here are the errors:

--- snip ---

% g++ -g -Wall -o calc.exe calc.cpp
calc.cpp: In function `int main()':
calc.cpp:18: warning: suggest parentheses around assignment used as truth value
calc.cpp:19: syntax error before `+='
% g++ -v
Using builtin specs.
gcc version 2.95.4 20020320 [FreeBSD]
%

--- snip ---

Code:

---

#include <iostream>

int  result;    // the result of the calculations
char  oper_char; // operator the user specified
int  value;      // value specified after the operator

int main()
{
  result = 0; // initialize the result

  // Loop forever ( or till we hit the break statement)
  while (true) {
    std::cout << "Result: " << result << '\n';

    std::cout << "Enter operator and number: ";
    std::cin >> oper_char >> value;

    if (oper_char = '+') {
      return += value;
    } else {
      std::cout << " Unknown operator " << oper_char << '\n';
    }
  }
  return (0);
}

---

1) Look up the difference between = and ==.

2) In your opinon what does this line do:

return += value;

When you write:

Code:

---

int num = 10;
num += 1;

---

that is short hand for:

Code:

---

int num = 10;
num = num + 1;

---

> if (oper_char = '+') {
Well = is assignment so hopefully it's a typo and should be ==:
if (oper_char == '+') {

> return += value;
This should probably be:
result += value;
return is a keyword is C/C++.