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.
e.g.
if(a>b)
{
---
---
}
else
{
---
---
}
1. Selection Statements
A selection statement provides the means of
choosing between two or more execution paths in a program.
e.g.
simple if
if else
Nested if
else if ladder
switch
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.
e.g.
for
while
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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