copy the N first characters of the given strings
res = strncpy(str1, num)
a character string or matrix of character strings.
an integer or a matrix of integers, maximum number of characters to be copied from source.
a character string or matrix of character strings.
res = strncpy(str1, num) copies the first num characters of source str1 to destination res.
num must have same dimensions than
str1 or num must be an integer number.