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Commands - 50

FOR / NEXT / STEP

Statements

SYNTAX: FOR variable = n TO m [STEP z]

PURPOSE: To perfor m a loop oper ation a given number of times.

REMARK S: n and m are positive (including zer o ) numbe rs and the optional z may be negative or positive, but

not 0.

n is the initial value of the counter. m is the final value of the counter. The pr ogram lines following

the FOR statement are executed until the NEX T statement is encounte red. Then the counter is

incremented by the amount specified by the STEP value z. If z is not specified, the increm ent is

assumed to be 1 (one). A check is performed to see if the value of the counter is now greater than

the final value m. If it is not greater, CAMBASIC branches back to the statement after the FOR

statement and the process is repeated. If it is greater, execution continues with the statement

following the NEXT statement. This is a FOR/ NEXT loop.

If z is negative, the test is reversed. The counter is decremented each time through the loop, and the

loop is executed until the counter is less than the final value.

The body of the loop is executed once if n is already greater than m when the STEP value is positive,

or if n is less than m when the STEP value is negative. If z is zero, an error will be displayed.

FOR/NEXT loops may be nested, that is, one FOR/NEXT loop may be placed inside another

FOR /NEXT loop. When loops are ne sted, each loop m ust have a unique varia ble name as its

counter. The NEXT statement for the inside loop must appear before the NEXT for the outside

loop.

EXAMPLE: 10 J=10 : K=30

20 FOR I=1 TO J STEP 2

30 PRINT I ;

40 K = K + 10

50 PRINT K

60 NEXT

1 40

3 50

5 60

7 70

9 80

ERROR: < NEXT w/o FOR> – if a NEXT is encountered without a corresponding FOR

< Data out of range> – if z = 0

1 2 ... 78 79 80 81 82 83 84 85 86 87 88 ... 207 208

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Remote-processing CAMBASIC Manual do Utilizador Página 83