Remote-processing CAMBASIC Manual do Utilizador descarregar pdf (Página 111)

Commands - 78

MID$

String Statement

SYNTAX: MID$(a$,s [,n]) = b$

PURPOSE: To replace a portion of one string with another.

REMARK S: A common usage for the MID$ statement is in networking protocols. The network commands are

standard strings defined by string variables.

Using the MID$ statement to modify these strings is much faster than other str ing methods.

The string a$ is the target string, while b$ is the replacement string.

The parameter s is the starting point within a$ where b$ will be inserted. The optional parameter n

indicates how many characters of b$ are to be used. W hen n is omitted, all of b$ is used.

If b$ is longer than a$, replacem ent will not exceed the length of a$. No error message will be

given.

RELATED: LEFT$, LEN, RIG HT$, INSTR, MID$ F unction

EXAMPLE: 10 F$ = "Hopeless"

20 R$ = "Help"

30 MID$(F$,1) = R$

40 PRINT F$

Helpless

The example below is for a comm unications protocol. Note that the escape cha racter is not a

printable character.

10 CV$=CHR(27) + "A" + "12"

20 MID$(CV$,3) = "23"

30 PRINT CV$

ESC A23

ERROR: < Data negative> – for s and n

< Data out of range> – if s = 0

< Data > 255> – for s and n

1 2 ... 106 107 108 109 110 111 112 113 114 115 116 ... 207 208

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Remote-processing CAMBASIC Manual do Utilizador Página 111