Substring/Top and tail
The task is to demonstrate how to remove the first and last characters from a string. The solution should demonstrate how to obtain the following results:
- String with first character removed
- String with last character removed
- String with both the first and last characters removed
You are encouraged to solve this task according to the task description, using any language you may know.
ALGOL 68
<lang algol68>#!/usr/local/bin/a68g --script #
STRING str="upraisers"; printf(($gl$,
str, # remove no characters # str[LWB str+1: ], # remove the first character # str[ :UPB str-1], # remove the last character # str[LWB str+1:UPB str-1], # remove both the first and last character # str[LWB str+2: ], # remove the first 2 characters # str[ :UPB str-2], # remove the last 2 characters # str[LWB str+1:UPB str-2], # remove 1 before and 2 after # str[LWB str+2:UPB str-1], # remove 2 before and one after # str[LWB str+2:UPB str-2] # remove both the first and last 2 characters #
))</lang> Output:
upraisers praisers upraiser praiser raisers upraise praise raiser raise
AWK
<lang awk>BEGIN {
mystring="knights" print substr(mystring,2) # remove the first letter print substr(mystring,1,length(mystring)-1) # remove the last character print substr(mystring,2,length(mystring)-2) # remove both the first and last character
}</lang>
C
<lang c>#include <string.h>
- include <malloc.h>
- include <stdio.h>
int main( int argc, char ** argv ){
char * str_a = "knight"; char * str_b = "socks"; char * str_c = "brooms";
char * new_a = malloc( (strlen( str_a ) - 1) ); char * new_b = malloc( (strlen( str_b ) - 1) ); char * new_c = malloc( (strlen( str_c ) - 2) );
strcpy( new_a, str_a + 1 ); strncpy( new_b, str_b, strlen( str_b ) - 1 ); strncpy( new_c, str_c + 1, strlen( str_c ) - 2 );
printf( "%s\n%s\n%s\n", new_a, new_b, new_c );
free( new_a ); free( new_b ); free( new_c );
return 0;
}</lang>
Result:
night sock room
ANSI C provides little functionality for text manipulation outside of string.h. While a number of libraries for this purpose have been written, this example uses only ANSI C.
D
Version for ASCII strings: <lang d>import std.stdio;
void main() {
writeln("knight"[1..$]); // strip first character
writeln("socks"[0..$-1]); // strip last character
writeln("brooms"[1..$-1]); // strip both first and last characters
}</lang>
Euphoria
<lang euphoria>function strip_first(sequence s)
return s[2..$]
end function
function strip_last(sequence s)
return s[1..$-1]
end function
function strip_both(sequence s)
return s[2..$-1]
end function
puts(1, strip_first("knight")) -- strip first character puts(1, strip_last("write")) -- strip last character puts(1, strip_both("brooms")) -- strip both first and last characters</lang>
Icon and Unicon
The task is accomplished by sub-stringing. <lang Icon>procedure main() write(s := "knight"," --> ", s[2:0]) # drop 1st char write(s := "sock"," --> ", s[1:-1]) # drop last write(s := "brooms"," --> ", s[2:-1]) # drop both end</lang>
It could also be accomplished (less clearly) by assigning into the string as below. Very awkward for both front and back. <lang Icon>write(s := "knight"," --> ", s[1] := "", s) # drop 1st char</lang>
J
The monadic primitives }. (Behead) and }: (Curtail) are useful for this task.
Example use:
<lang j> }. 'knight' NB. drop first item
night
}: 'socks' NB. drop last item
sock
}: }. 'brooms' NB. drop first and last items
room</lang>
Java
I solve this problem two ways. First I use substring which is relatively fast for small strings, since it simply grabs the characters within a set of given bounds. The second uses regular expressions, which have a higher overhead for such short strings.
<lang Java>public class RM_chars {
public static void main( String[] args ){
System.out.println( "knight".substring( 1 ) );
System.out.println( "socks".substring( 0, 4 ) );
System.out.println( "brooms".substring( 1, 5 ) );
// first, do this by selecting a specific substring
// to exclude the first and last characters
System.out.println( "knight".replaceAll( "^.", "" ) );
System.out.println( "socks".replaceAll( ".$", "" ) );
System.out.println( "brooms".replaceAll( "^.|.$", "" ) );
// then do this using a regular expressions
}
}</lang>
Results:
night sock room night sock room
JavaScript
<lang javascript>alert("knight".slice(1)); // strip first character alert("socks".slice(0, -1)); // strip last character alert("brooms".slice(1, -1)); // strip both first and last characters</lang>
Lua
<lang lua>print (string.sub("knights",2)) -- remove the first character print (string.sub("knights",1,-2)) -- remove the last character print (string.sub("knights",2,-2)) -- remove the first and last characters</lang>
PARI/GP
<lang parigp>df(s)=concat(vecextract(Vec(s),1<<#s-2)); dl(s)=concat(vecextract(Vec(s),1<<(#s-1)-1)); db(s)=concat(vecextract(Vec(s),1<<(#s-1)-2));</lang>
Perl
<lang perl>print substr("knight",1), "\n"; # strip first character print substr("socks", 0, -1), "\n"; # strip last character print substr("brooms", 1, -1), "\n"; # strip both first and last characters</lang>
In perl, we can also remove the last character from a string variable with the chop function:
<lang perl>$string = 'ouch'; $bits = chop($string); # The last letter is returned by the chop function print $bits; # h print $string; # ouc # See we really did chop the last letter off</lang>
PHP
<lang php><?php echo substr("knight", 1), "\n"; // strip first character echo substr("socks", 0, -1), "\n"; // strip last character echo substr("brooms", 1, -1), "\n"; // strip both first and last characters ?></lang>
PicoLisp
<lang PicoLisp>: (pack (cdr (chop "knight"))) # Remove first character -> "night"
- (pack (head -1 (chop "socks"))) # Remove last character
-> "sock"
- (pack (cddr (rot (chop "brooms")))) # Remove first and last characters
-> "room"</lang>
Prolog
Works with SWI-Prolog.
<lang Prolog>remove_first_last_chars :- L = "Rosetta", L = [_|L1], remove_last(L, L2), remove_last(L1, L3), writef('Original string : %s\n', [L]), writef('Without first char : %s\n', [L1]), writef('Without last char : %s\n', [L2]), writef('Without first/last chars : %s\n', [L3]).
remove_last(L, LR) :- reverse(L, [_ | L1]), reverse(L1, LR).</lang> Output :
?- remove_first_last_chars. Original string : Rosetta Without first char : osetta Without last char : Rosett Without first/last chars : osett true.
PureBasic
<lang PureBasic>If OpenConsole()
PrintN(Right("knight", Len("knight") - 1)) ;strip the first letter
PrintN(Left("socks", Len("socks")- 1)) ;strip the last letter
PrintN(Mid("brooms", 2, Len("brooms") - 2)) ;strip both the first and last letter
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf</lang> Sample output:
night sock room
Python
<lang python>print "knight"[1:] # strip first character print "socks"[:-1] # strip last character print "brooms"[1:-1] # strip both first and last characters</lang>
Ruby
<lang ruby>puts "knight"[1..-1] # strip first character puts "socks"[0..-2] # strip last character puts "socks".chop # alternate way to strip last character puts "brooms"[1..-2] # strip both first and last characters</lang>
Tcl
<lang tcl>puts [string range "knight" 1 end]; # strip first character puts [string range "write" 0 end-1]; # strip last character puts [string range "brooms" 1 end-1]; # strip both first and last characters</lang>
ZX Spectrum Basic
<lang zxbasic>10 PRINT FN f$("knight"): REM strip the first letter 20 PRINT FN l$("socks"): REM strip the last letter 30 PRINT FN b$("brooms"): REM strip both the first and last letter 100 STOP
9000 DEF FN f$(a$)=a$(2 TO LEN(a$)) 9010 DEF FN l$(a$)=a$(1 TO LEN(a$)-(1 AND (LEN(a$)>=1))) 9020 DEF FN b$(a$)=FN l$(FN f$(a$)) </lang>