Get span of character set in string
res = strspn(str1,str2)
:str1 A character string or matrix of character strings : :str2 A character string or matrix of character strings : :res matrix. :
res = strspn(str1,str2) Returns the length of the initial portion of str1 which consists only of characters that are part of str2.
str1 must have same dimensions than str2 or str1 must be a string.
i = strspn("129th","1234567890");
`mprintf`_ ("The length of initial number is %d.\n",i);
i = strspn(["129th","130th"],["1234567890","130t"])