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book: add some additional details on strings

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FossilOrigin-Name: aebd04b864161c8b0539ff56735584004e47c2a400a27ee02a553fb3fde3ef82
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crc 2019-03-21 17:39:38 +00:00
parent 6c1661dd31
commit f9f49ec75f
2 changed files with 102 additions and 6 deletions
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54
RETRO-Book.md
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@ -1687,9 +1687,27 @@ RETRO provides four words for searching within a string.
## Extraction
`s:left`
`s:right`
`s:substr`
To obtain a new string containing the first `n` characters from
a source string, use `s:left`:
```
'Hello_World #5 s:left
```
To obtain a new string containing the last `n` characters from
a source string, use `s:right`:
```
'Hello_World #5 s:right
```
If you need to extract data from the middle of the string, use
`s:substr`. This takes a string, the offset of the first
character, and the number of characters to extract.
```
'Hello_World #3 #5 s:substr
```
## Joining
@ -1746,6 +1764,36 @@ which let you trim just the leading or trailing end as desired.
`s:format`
`s:empty`
## Controlling The Temporary Buffers
As dicussed in the Lifetime subsection, temporary strings are
allocated in a rotating buffer. The details of this can be
altered by updating two variables.
| Variable | Holds |
| ------------- | ---------------------------------------- |
| TempStrings | The number of temporary strings |
| TempStringMax | The maximum length of a temporary string |
For example, to increase the number of temporary strings to
48:
```
#48 !TempStrings
```
The defaults are:
| Variable | Default |
| ------------- | ------- |
| TempStrings | 32 |
| TempStringMax | 512 |
It's also important to note that altering these will affect
the memory map for all temporary buffers. Do not use anything
already in the buffers after updating these or you will risk
data corruption and possible crashes.
# The Return Stack

54
book/Programming-Techniques-Working-With-Strings
View file

@ -68,9 +68,27 @@ RETRO provides four words for searching within a string.
## Extraction
`s:left`
`s:right`
`s:substr`
To obtain a new string containing the first `n` characters from
a source string, use `s:left`:
```
'Hello_World #5 s:left
```
To obtain a new string containing the last `n` characters from
a source string, use `s:right`:
```
'Hello_World #5 s:right
```
If you need to extract data from the middle of the string, use
`s:substr`. This takes a string, the offset of the first
character, and the number of characters to extract.
```
'Hello_World #3 #5 s:substr
```
## Joining
@ -126,3 +144,33 @@ which let you trim just the leading or trailing end as desired.
`s:replace`
`s:format`
`s:empty`
## Controlling The Temporary Buffers
As dicussed in the Lifetime subsection, temporary strings are
allocated in a rotating buffer. The details of this can be
altered by updating two variables.
| Variable | Holds |
| ------------- | ---------------------------------------- |
| TempStrings | The number of temporary strings |
| TempStringMax | The maximum length of a temporary string |
For example, to increase the number of temporary strings to
48:
```
#48 !TempStrings
```
The defaults are:
| Variable | Default |
| ------------- | ------- |
| TempStrings | 32 |
| TempStringMax | 512 |
It's also important to note that altering these will affect
the memory map for all temporary buffers. Do not use anything
already in the buffers after updating these or you will risk
data corruption and possible crashes.