String MAT Statements

Let A$ and B$ be string arrays.

MAT A$=nul$
assigns the empty string to all elements of A$

Let s$ be a string expression.
MAT A$=(s$) & nul$
assigns s$ to all elements of A$
When s$ is a string variable, a string constant, or a string function reference, the parentheses can be omitted.

MAT A$(m:n)=(s$) & nul$
replace the m-th character to the n-th character of A$ with s$.

Le A$ be 1-dimensional and the lower bound of it be equal to option base.
MAT A$=nul$(n)
changes the upper bound of A$ to n, and assigns the empty string to all elements.

Le A$ be 2-dimensional and the lower bounds of it be equal to option base.
MAT A$=nul$(m,n)
changes the upper bounds of A$ to m and n, and assigns the empty string to all elements.

Let A$ and B$ have the same dimension and the same lower bounds.
MAT A$=B$
substitutes B$ for A$.

Let A$ and B$ have the same size.
MAT A$(m:n)=B$
Replace the m-th character to n-th character of A$ with B$.

Let B$ and C$ have the same size and the same dimension as A$.
MAT A$=B$ & C$
Substitutes an array that is obtained by concatenating each element of B$ and each element of C$ for A$.

Let A$ and B$ have the same dimension, s$ be a string expression.
MAT A$=(s$) & B$
Substitutes an array that is obtained by concatenating s$ and each element of B$ for A$.
MAT A$=B$ & (s$)
Substitutes an array that is obtained by concatenating each element of B$ and s$ for A$.