The research of Bohm and Jacopini demonstrated that programs could be written without goto statements.1 The challenge of the era for programmers was to shift their
styles to “goto-less programming.” It was not until the 1970s that programmers started taking structured programming seriously. The results were impressive, as software devel-opment groups reported reduced development times, more frequent on-time delivery of systems and more frequent within-budget completion of software projects. The key to these successes is that structured programs are clearer, easier to debug and modify and more likely to be bug free in the first place.
A flowchart is a graphical representation of an algorithm or of a portion of an algo-rithm. Flowcharts are drawn using certain special-purpose symbols, such as rectangles, dia-monds, ovals and small circles; these symbols are connected by arrows called flowlines, which indicate the order in which the actions of the algorithm execute.
Like pseudocode, flowcharts often are useful for developing and representing algo-rithms, although pseudocode is strongly preferred by many programmers. Flowcharts show clearly how control structures operate; that is all we use them for in this text. Care-fully compare the pseudocode and flowchart representations of each control structure.
In a flowchart that represents a complete algorithm, an oval symbol containing the word “Begin” is the first symbol used; an oval symbol containing the word “End” indicates where the algorithm ends. In a flowchart that shows only a portion of an algorithm, as in Fig. 7.1, the oval symbols are omitted in favor of using small circle symbols, also called connector symbols.
Perhaps the most important flowcharting symbol is the diamond symbol, also called the decision symbol, which indicates that a decision is to be made. We discuss the dia-mond symbol in the next section.
forms an action if a condition is true and performs a different action if the condition is false. The switch selection statement (Chapter 8) performs one of many different actions, depending on the value of an expression.
The if statement is called a single-selection structure because it selects or ignores a single action (or, as we will soon see, a single group of actions). The if…else statement is a double-selection structure because it selects between two different actions (or groups of actions). The switch statement is a multiple-selection structure because it selects among many different actions (or groups of actions).
break case catch continue default
delete do else false finally
for function if in instanceof
new null return switch this
throw true try typeof var
void while with
abstract boolean byte char class
const debugger double enum export
extends final float goto implements
import int interface long native
package private protected public short
static super synchronized throws transient
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