Linxutopia - Thinking in C++ - 3: The C in C++

Thinking in C++
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if-else

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The if-else statement can exist in two forms: with or without the else. The two forms are:

if(expression)
    statement

if(expression)
    statement
else
    statement

The “expression” evaluates to true or false. The “statement” means either a simple statement terminated by a semicolon or a compound statement, which is a group of simple statements enclosed in braces. Any time the word “statement” is used, it always implies that the statement is simple or compound. Note that this statement can also be another if, so they can be strung together.

//: C03:Ifthen.cpp
// Demonstration of if and if-else conditionals
#include <iostream>
using namespace std;

int main() {
  int i;
  cout << "type a number and 'Enter'" << endl;
  cin >> i;
  if(i > 5)
    cout << "It's greater than 5" << endl;
  else
    if(i < 5)
      cout << "It's less than 5 " << endl;
    else
      cout << "It's equal to 5 " << endl;

  cout << "type a number and 'Enter'" << endl;
  cin >> i;
  if(i < 10)
    if(i > 5)  // "if" is just another statement
      cout << "5 < i < 10" << endl;
    else
      cout << "i <= 5" << endl;
  else // Matches "if(i < 10)"
    cout << "i >= 10" << endl;
} ///:~

It is conventional to indent the body of a control flow statement so the reader may easily determine where it begins and ends[30].

Thinking in C++
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