Rockwell-automation 2098-IPD-xxx Ultra5000 C Programming using the Mot Manuel d'utilisateur télécharger pdf (Page 35)

Publication 2098-PM001E-EN-P — July 2002

Programming Motion Control in C 1-23

Control Flow

In this section you will learn about the functions that control the flow

of a C program. The functions include:

• Statements and Blocks

• If-Else

• Else-If

• Switch

• While, For and Do-While Loops

• Break and Continue

Statements and Blocks

A statement is a command to the computer. In C, any expression

followed by a semicolon forms a statement. A statement may or may

not do something. For example the statement,

long point;

declares the variable point, but the null statement (a semicolon by

itself)

;

does nothing.

A block is two or more statements grouped together by enclosing

them in braces. The braces cause the entire block to be evaluated as a

single statement. Without the braces, each statement terminating with

a semicolon is evaluated separately. Refer to the following two

grouping examples.

Example 8 - Grouping Statements

/* grouping example A - individual statements */

point = 0;

while (point++ < 12)

target = 10 * point + 2;

MoveAbsolute(target);

/* grouping example B - blocked statements */

point = 0;

while (point++ < 12)

{

target = 10 * point + 2;

MoveAbsolute(target);

}

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