(C++) if

Keyword that checks a condition. If a condition is true, then it performs the statement(s) after if, else it performs the statement(s) after else.

include <iostream>

int main()
{
  //A coin-toss
  if (rand()%2==0)
  {
    std::cout << "You threw head." << std::endl;
  }
  else
  {
    std::cout << "You threw tail." << std::endl;
  }
  return 0;
}

The if-statement can be used for debugging by checking certain values. If you do so, check the use of assert, which is an if-statement that can be 'removed' from you code by the preprocessor.

Syntax

This program shows the syntaxes of if and if..else. It also puts wise words on the screen

include <iostream>


int main()
{
  //Multiple statements using accolades '{' and '}'
  if (1==2) 
  {
    for (int i=0; i!=10; ++i)
    {
      std::cout << "Life is bad." << std::endl;
    }
  }
  else 
  {
    for (int i=0; i!=10; ++i)
    {
      std::cout << "Life is good." << std::endl;
    }
  }
  //You can skip accolades for a single statement
  if (1==2) std::cout << "Life is bad." << std::endl; //One statement
  else std::cout << "Life is good." << std::endl; //One statement
  //The else condition is not obligatory
  if (1==2) std::cout << "Life is bad." << std::endl; //One statement
  std::cout << "Today you should go to the pub." << std::endl; 
  return 0;
}

if in debugging

When you use if's for debugging, prefer using either try and catch or assert statements. These both have their own strengths, so see them both.

Code links

'if' links

last edited (November 24, 2006) by bilderbikkel, Number of views: 4690, Current Rev: 11 (Diff)

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