Ruby代码
def map_method
arr1 = ["name2","class2"]
arr2 = arr1.map {|num| num + "and"}
print "map............",arr2,"n"
end
def each_method
arr1 = ["name2","class2"]
arr2 = arr1.each {|num| num + "and"}
print "each............","n"
end
def collect_method
arr1 = ["name2","class2"]
arr2 = arr1.collect {|num| num + "and"}
print "collect............","n"
end
def map1_method
arr1 = ["name2","class2"]
arr2 = arr1.map! {|num| num + "and"}
print "map!............","n"
end
def collect1_method
arr1 = ["name2","class2"]
arr2 = arr1.collect! {|num| num + "and"}
print "collect!............","n"
end
def test
map_method
each_method
collect_method
map1_method
collect1_method
end
test
result：
map............["name2and","class2and"]
each............["name2","class2"]
collect............["name2and","class2and"]
map!............["name2and","class2and"]
collect!............["name2and","class2and"]
为了更明了的了解each的用法，看下面的例子：
Ruby代码
def each_deep_method
arr_test = [1,2,3]
arr_result = arr_test.each do |num|
num = num + 1
p num
end
arr_result
end
result:
2
3
4
=> [1,3]
可见each_deep_method的返回值arr_result是和arr_test相等的。
[总结]
(1)each只是遍历数组的每个元素，并不生成新的数组；
(2)map和collect相同用法，遍历每个元素，用处理之后的元素组成新的数组，并将新数组返回；
(3)map！同collect！
其中map和map！、collect和collect!的区别就不用纠结了吧，实在纠结就看下面的例子：
Ruby代码
def map_deep_method
arr_test = [1,3]
arr_test.map do |num|
num += 1
end
arr_test #[1, 2, 3]
end
def map1_deep_method
arr_test = [1,3]
arr_test.map! do |num|
num += 2
end
arr_test #[3, 4, 5]
end
