Monday 19 April 2021

Statement Level Control Structures | Selection Iterative Statements | Unconditional Branching | PPL

                    In this post, we will see Statement Level Control Structures | Selection Statements | Iterative Statements | Unconditional Branching | PPL | Sebesta | statement level control structures, selection statements, iterative statements, unconditional branching, ppl, sebesta   

Statement level Control Statements:

              Two linguistic mechanisms which are necessary to make the computations in programs flexible and powerful: some means of selecting among alternative control flow paths (of statement execution) and some means of causing the repeated execution of statements or sequences of statements.

              Statements that provide these kinds of capabilities are called control statements.


              It was proven that all algorithms that can be expressed by flowcharts can be coded in a programming language with only two control statements:

one for choosing between two control flow paths and one for logically controlled iterations (Böhm and Jacopini, 1966). 


              A control structure is a control statement and the collection of statements whose execution it controls.














1. Selection Statements

              A selection statement provides the means of choosing between two or more execution paths in a program.



simple if

if else

Nested if

else if ladder



2. Iterative Statements

              An iterative statement is one that causes a statement or collection of statements to be executed zero, one, or more times.

              An iterative statement is often called a loop.




do while



3. Unconditional Branching

              An unconditional branch statement transfers execution control to a specified location in the program.

              Without restrictions on use, imposed by either language design or programming standards, goto statements

can make programs very difficult to read, and as a result, highly unreliable and costly to maintain.

              A few languages have been designed without a goto for example, Java, Python, and Ruby.

              The relatively new language, C#, includes a goto, even though one of the languages on which it is based, Java, does not.

e.g. goto statement

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