Operators in MQL4

void OnStart()
{
   /*
   Compound operator is a group of operators contained between curly brackets { }
   */
   if (1 == 1)
   {
      Print("Hello");
      Print("World");
   }  
}

void OnStart()
{
   // The semicolon ; terminates the line.
   // The equal sign = assigns a value.
   int a = 10;
   string s = "Hello";
}

void OnStart()
{
   // Conditional operators execute an action depending on whether a condition is verified.
   // These can be categorized as conditional: if-else, switch-case, and tertiary operator ?

   int i = 10;

   // "if" executes an action if the condition is verified.
   if (i > 0)
   {
      Print("i is big"); // Program prints "i is big" if i is greater than 0.
   }
   else Print("i is small"); // Program prints "i is small" if i is 0 or a negative number.

   // "switch-case" checks a variable/expression over a value and performs the associated action.
   switch(i)
   {
      case 1:
      Print("i is 1"); // Program prints "i is 1" if i has value 1, then it exits the switch case.
      break;
      case 10:
      Print("i is 10"); // Program prints "i is 10" if i has value 10, then it exits the switch case.
      break;
      default:
      Print("i is not 1 or 10"); // Program prints "i is not 1 or 10" if none of the conditions is verified.
      break; // Then it exits the switch case.
   }
   // The tertiary operator may be tricky: it checks a condition and if true, it assigns the first value;
   // if false, it assigns the second value.
   int j = (i == 10) ? 1 : 0; // If i is equal to 10 j is assigned the value 1, otherwise it is assigned 0.
}

void OnStart()
{
   // Loop operators perform the same action a number of times, that is why they are called "loop operators".
   // These operators are: "for", "while", and "do while". And they have some differences.
   
   // The loop "for" defines a variable i = 1 and prints it for as long as i <= 10,
   // i is incremented with i++ at each execution.
   // This loop will print the sequence of numbers from 1 to 10:
   for (int i = 1; i <= 10; i++)
   {
      Print(i);
   }
   
   i = 1;
   // "while" is similar to "for", but the variable is defined beforehand,
   // and the body of the loop must include the update of the variable.
   // This loop will also print the sequence of numbers from 1 to 10.
   while (i <= 10)
   {
      Print(i);
      i++;
   }
   
   i = 1;
   // "do while" is similar to the previous two,
   // but the big difference is that the condition is checked after the execution.
   // This means that "do while" is always executed at least once.
   // This "do while" will print the sequence of numbers from 1 to 10 too.
   do
   {
      Print(i);
      i++;
   }
   while(i <= 10);
}