MID$(string-expression, integer-expression, integer-expression)

Returns a substring of the given string, starting at the position given by the first integer parameter and extending for the length given by the second.

Examples

PRINT MID$("RetroRocket", 0, 5)

Produces "Retro".

PRINT MID$("RetroRocket", 5, 6)

Produces "Rocket".

REM Extract file extension
filename$ = "document.txt"
PRINT MID$(filename$, LEN(filename$) - 3, 3)

Produces "txt".

Notes

Positions are zero-based: the first character of the string is at index 0.
If the length extends beyond the end of the string, the substring is truncated.
If the starting index is beyond the string length, the result is an empty string.
Negative positions or lengths cause an error.

See also: LEFT$ · RIGHT$ · LEN