6.3.5 First character, middle and end of a string: head mid tail
The head command finds the first character of a string.
-
head takes one argument:
str, a string.
- head(str) returns the first
character of the string str.
Example.
Input:
head("Hello")
Output:
"H"
The mid command finds a selected part from the middle of a
string.
-
mid takes three arguments:
-
str, a string.
- p, an integer for the starting index of the result.
- q, an integer q for the length of the string.
- mid(str,p,q) returns the part of
the string str starting with the character at index p with length
q. (Remember that the first index is 0 in Xcas mode.)
Example.
Input:
mid("Hello",1,3)
Output:
"ell"
The tail command removes the first character of a string.
-
tail takes one argument:
str, a string.
- tail(str) returns the string
str without its first character.
Input:
tail("Hello")
Output:
"ello"