"Write a method which will remove any given character from a String"

removeChar.groovy

// "Write a method which will remove any given character from a String" 
// The method will be the 'minus' method 'some string ' - 's' == 'ome tring'

def check() {
  assert 'some string' - 's' == 'ome tring'
  assert '' - 'a' == ''
  assert 'something else' - 'z' == 'something else'
}

// Easy one
String.metaClass.minus { String c -> // careful, String already has a 'minus' method, if we override the one in CharSequence, it won't work
  delegate.replaceAll(c, '')
}

check()

// Non-cheating one
String.metaClass.minus { String toRemove ->
  StringBuffer buff = ''<<''
  delegate.each { c ->
    if (c != toRemove) buff << c
  }
  buff as String
}

check()​