is jump back up (goto), while in structured programming this is an indefinite loop (while loop) set to never end, either by omitting the condition or explicitly setting it to true, as while (true) .... Some languages have special constructs for infinite loops, typically by omitting the condition from an indefinite loop. Examples include Ada (loop ... end loop), Fortran (DO ... END DO), Go (for { ... }), and Ruby (loop do ... end). Often, an infinite loop is unintentionally created by a programming error in a condition-controlled loop, wherein the loop condition uses variables that never change within the loop. Continuation with next iteration Sometimes within the body of a loop there is a desire to skip the remainder of the loop body and continue with the next iteration of the loop. Some languages provide a statement such as continue (most languages), skip, or next (Perl and Ruby), which will do this. The effect is to prematurely terminate the innermost loop body and then resume as normal with the next iteration. If the iteration is the last one in the loop, the effect is to terminate the entire loop early. Redo current iteration Some languages, like Perl and Ruby, have a redo statement that restarts the current iteration from the start. Restart loop Ruby has a retry statement that restarts the entire loop from the initial iteration. Early exit from loops When using a count-controlled loop to search through a table, it might be desirable to stop searching as soon as the required item is found. Some programming languages provide a statement such as break (most languages), Exit (Visual Basic), or last (Perl), which effect is to terminate the current loop immediately, and transfer control to the statement immediately after that loop. Another term for early-exit loops is loop-and-a-half. The following example is done in Ada which supports both early exit from loops and loops with test in the middle. Both features are very similar and comparing both code snippets will show the difference: early exit must be combined with an if statement while a condition in the middle is a self-contained construct. with Ada.Text IO; with Ada.Integer Text IO; procedure Print_Squares is X : Integer; begin Read_Data : loop Ada.Integer Text IO.Get(X); exit Read_Data when X = 0; Ada.Text IO.Put (X * X); Ada.Text IO.New_Line; end loop Read_Data; end Print_Squares; Python supports conditional execution of code depending