# NUMCHK

> [HTML Version](numchk_sbr.htm)

**xcall NUMCHK, string \{,len, rc\}**

NUMCHK checks a string to see if it contains valid numeric characters only, and possibly that it is of a certain length.

**Parameters**

_string_  ([String](string.htm.md))  \[in/out\]

string to be searched. _string_ is stripped of leading and trailing spaces and tabs and returned that way, regardless of whether valid.

_len_  ([Num](num.htm.md))  \[in\]

if specified, stripped _string_ length must match.

_rc_  (F6)  \[out\]

optional return value specifying okay (0), or that _string_ contains invalid characters or is not of _len_ length (-1). Note that NUMCHK may be passed to the [XFUNC](xfunc().htm.md) function, in which case rc is not really relevant since the function itself returns the same value.