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Looping Commands

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Looping commands control execution flow of your script. If you wanted to print the word NinjaTrader 100 times, you could either use 100 lines of code or do the same using a looping command in only a few lines of code.

While Loop

1while (Boolean expression)
2{
3     //Do something here
4}
1// Print NinjaTrader 100 times to the output window
2int x = 0;
3while (x < 100)
4{
5      Print("NinjaTrader");
6      x = x + 1;
7}

Do While Loop

1do
2{
3     //Do something here
4}
5while (Boolean expression)
1// Print NinjaTrader 100 times to the output window
2int x = 0;
3do
4{
5      Print("NinjaTrader");
6      x = x + 1;
7}
8while (x < 100)

For Loop

1for (initializer; boolean expression; iterator)
2{
3     //Do something here
4}
1// Print NinjaTrader 100 times to the output window
2for (int x = 0; x < 100; x++)
3{
4      Print("NinjaTrader");
5}
1// Print NinjaTrader 100 times to the output window
2for (int x = 0; x < 100; x++)
3{
4      Print("NinjaTrader");
5}

Foreach Loop

1foreach (type identifier in boolean expression)
2{
3     // Do something here
4}
1// Count the number of oatmeal cookies in a cookie jar
2int oatmealCookies = 0;
3foreach (cookie in cookieJar)
4{
5*      if (cookie.Type == Oatmeal)
6      {
7          oatmealCookies = oatmealCookies + 1;
8      }
9}
10Print("There are " + numberOatmeal.ToString() + " oatmeal cookies in the cookie jar.");

Break and Continue

You can use the break command to exit a loop at any time. The following example is an infinite loop, but we will break out after the first Print statement.

1// Exit the infinite loop after the first iteration
2* while (0 == 0)
3* {
4      Print("NinjaTrader");
5      break;
6}

The continue command will jump ahead to the next iteration of the loop. The following example will never print NinjaTrader, because the continue command sends control back to the top of the loop each time.

1// Never prints "NinjaTrader"
2
3for (int x = 0; x < 100; x++)
4{
5      continue;
6      Print("NinjaTrader");
7}
1// Never prints "NinjaTrader"
2for (int x = 0; x < 100; x++)
3{
4      continue;
5      Print("NinjaTrader");
6}