Q8a

type string=record length:integer; C:array[1..100] of char end

Substring (s, i, j): this yields the string made up of the $i^{\text{th}}$ through $j^{\text{th}}$ characters in s; for appropriately defined in $i$ and $j$.

Contact $(s_{1}, s_{2})$: this function yields a string of length $s_{1}$ length + $s_{2}$ - length obtained by concatenating $s_{1}$ with $s_{2}$ such that $s_{1}$ precedes $s_{2}$.