---
name: "Tk_GetDash"
section: "3tk"
platform: "linux"
package: "tk8.6-doc"
version: "8.6.16-1"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Tk_GetDash/3tk"
---

# Tk\_GetDash(3tk)

convert from string to valid dash structure.

```

```

## NAME

Tk\_GetDash - convert from string to valid dash structure.

## SYNOPSIS

```
#include <tk.h>
int
Tk_GetDash(interp, string, dashPtr)
```

## ARGUMENTS

- Tcl\_Interp *\*interp* (in)

  Interpreter to use for error reporting.

- const char *\*string* (in)

  Textual value to be converted.

- Tk\_Dash *\*dashPtr* (out)

  Points to place to store the dash pattern value converted from *string*. Must not be NULL.

  ```

  ```

## DESCRIPTION

These procedure parses the string and fills in the result in the Tk\_Dash structure. The string can be a list of integers or a character string containing only “**.,-\_**” and spaces. If all goes well, **TCL\_OK** is returned and a dash descriptor is stored in the variable pointed to by *dashPtr*. If *string* does not have the proper syntax then **TCL\_ERROR** is returned, an error message is left in the interpreter's result, and nothing is stored at \**dashPtr*.

The first possible syntax is a list of integers. Each element represents the number of pixels of a line segment. Only the odd segments are drawn using the “outline” color. The other segments are drawn transparent.

The second possible syntax is a character list containing only 5 possible characters “**.,-\_** ”. The space can be used to enlarge the space between other line elements, and can not occur in the first position of the string. Some examples:

```
    -dash .     = -dash {2 4}
    -dash -     = -dash {6 4}
    -dash -.    = -dash {6 4 2 4}
    -dash -..   = -dash {6 4 2 4 2 4}
    -dash {. }  = -dash {2 8}
    -dash ,     = -dash {4 4}
```

The main difference between this syntax and the numeric is that it is shape-conserving. This means that all values in the dash list will be multiplied by the line width before display. This ensures that “.” will always be displayed as a dot and “-” always as a dash regardless of the line width.

On systems where only a limited set of dash patterns, the dash pattern will be displayed as the most close dash pattern that is available. For example, on Windows only the first 4 of the above examples are available; the last 2 examples will be displayed identically to the first one.

## SEE ALSO

[canvas(3tk)](/canvas/3tk.md), [Tk\_CreateItemType(3tk)](/Tk_CreateItemType/3tk.md)

## KEYWORDS

dash, conversion