Atari 800 Basic Reference Manual

LEN
STR$
VAL
38 Strings
10 FOR I=0 TO 25
~'0 PR I HT CHfU( ASC( .. A
11
)+I ) ) CHF.:$( A: :;C( "a" )+
I)
30 t·~E>=:T I
Figure 7-2. ASC and CHR$ Program Example
Note: There can be only one STR$ and only one CHR$ in a logical comparison.
Format:
LEN (sexp)
Example:
100 PRINT LEN(A$)
This function returns the length in bytes of the designated string . This informa-
tion may then be printed or used later in a program. The length of a string
variable is simply the index for the character which is currently at the end of
the string . Strings have a length ofO until characters have been stored in them.
It is possible to store into the middle of the string by using sub sc ripting.
However, the beginning of the string will contain garbage unless something
was stored (using STO) there previously.
The following routine illustrates one use of the LEN function:
10 Dir-1 A!( 10 >
2~3 A:i=u AT A~~ In
3( 1 F'~~ I f -~T LEt·i< A$ >
Figure 7-3. LEN Function Example
The result ofrunning the above program would be 5.
Format:
Example:
STR$ (aexp)
A$= STR$(65)
This string from number function returns the string form of the number in
parentheses . The above example would return the actual number 65, but it
would be recognized by the computer as a str ing .
Note: There can only be one STR$ and only one CHR$ in a logical comparison.
F or exa mple , A= STR$(1) > STR$(2) is not valid and will not wor k cor:rectly.
Format:
VAL(sexp)
Example:
100 A = V AL(A$)
This function returns a number of the same value as the number stored as a
string. This is the opposite of a STR$ function. Usi ng this function , the computer
can perform arithm e ti c operations on strings as s ho w n in th e following e xam-
ple program:
10 DH1 8$(5)
20 B:f.: II 10(10(11!
30 E:=SG!~\ I..JAL( B$) )
40 PRHH
11
THE SQUAPE POOT OF II , ;8$ .; II IS II
jB
Figure 7-4. VAL Function Program

Atari 800 Specifications

General

Brand	Atari
Model	800
Category	Desktop
Language	English