map中的lower_bound和upper_bound的意思其实很简单，就两句话：
map::lower_bound(key):返回map中第一个大于或等于key的迭代器指针
map::upper_bound(key):返回map中第一个大于key的迭代器指针
所以，理解这两个函数请不要按照字面意义思考太复杂，因为仅仅是不小于（lower_bound）和大于（upper_bound）这么简单。
看两个msdn里的例子
// map_upper_bound.cpp
// compile with: /EHsc
#include &map&
#include &iostream&
int main( )
map &int, int& m1;
map &int, int& :: const_iterator m1_AcIter, m1_RcI
typedef pair &int, int& Int_P
m1.insert ( Int_Pair ( 1, 10 ) );
m1.insert ( Int_Pair ( 2, 20 ) );
m1.insert ( Int_Pair ( 3, 30 ) );
　　// 返回m1中第一个key值大于或等于2的元素的迭代器，当然是&2,20&　m1_RcIter = m1.upper_bound( 2 );
cout && "The first element of map m1 with a key "
&& "greater than 2 is: "
&& m1_RcIter -& second && "." &&
// If no match is found for the key, end is returned
m1_RcIter = m1. upper_bound ( 4 );
& &// m1中key值并没有大于或等于4的&
& &if ( m1_RcIter == m1.end( ) )
cout && "The map m1 doesn't have an element "
&& "with a key greater than 4." &&
cout && "The element of map m1 with a key & 4 is: "
&& m1_RcIter -& second && "." &&
// The element at a specific location in the map can be found
// using a dereferenced iterator addressing the location
m1_AcIter = m1.begin( );
m1_RcIter = m1. upper_bound ( m1_AcIter -& first );
cout && "The 1st element of m1 with a key greater than\n"
&& "that of the initial element of m1 is: "
&& m1_RcIter -& second && "." &&
The first element of map m1 with a key greater than 2 is: 30.
The map m1 doesn't have an element with a key greater than 4.
The 1st element of m1 with a key greater than
that of the initial element of m1 is: 20.
// map_lower_bound.cpp
// compile with: /EHsc
#include &map&
#include &iostream&
int main( )
map &int, int& m1;
map &int, int& :: const_iterator m1_AcIter, m1_RcI
typedef pair &int, int& Int_P
m1.insert ( Int_Pair ( 1, 10 ) );
m1.insert ( Int_Pair ( 2, 20 ) );
m1.insert ( Int_Pair ( 3, 30 ) );
　　//key值大于2的是&3,30&
m1_RcIter = m1.lower_bound( 2 );
cout && "The first element of map m1 with a key of 2 is: "
&& m1_RcIter -& second && "." &&
// If no match is found for this key, end( ) is returned
m1_RcIter = m1. lower_bound ( 4 );
if ( m1_RcIter == m1.end( ) )
cout && "The map m1 doesn't have an element "
&& "with a key of 4." &&
cout && "The element of map m1 with a key of 4 is: "
&& m1_RcIter -& second && "." &&
// The element at a specific location in the map can be found
// using a dereferenced iterator addressing the location
m1_AcIter = m1.end( );
m1_AcIter--;
m1_RcIter = m1. lower_bound ( m1_AcIter -& first );
cout && "The element of m1 with a key matching "
&& "that of the last element is: "
&& m1_RcIter -& second && "." &&
The first element of map m1 with a key of 2 is: 20.
The map m1 doesn't have an element with a key of 4.
The element of m1 with a key matching that of the last element is: 30.
阅读(...) 评论()用英语怎么写?_百度作业帮
拍照搜题，秒出答案
用英语怎么写?
用英语怎么写?
nine two one six six six four five eight
nine hundred and twenty own billin six hundred and sixty six millin four hundred and fifty eight
如果是电话号等专用号码，为nine two one six six six four five eight如果是一个数字，为nine hundred and twenty-one million,six hundred and sixty-six thousand,four hundred and fifty-eight.How Much is
a Billion?
10) How much is a billion?
A billion, in America, is a thousand million.
That would be written like this:
1,000,000,000
If we wanted to make a book with a billion
dollar signs, printed 1000 per page as before and with pages printed
on both sides, our book would be 500,000 pages long.Now that's a very
long book!
Interestingly, in England, the British define a
billion as a million million. That would be 1,000,000 times 1,000,000
which would be written like this:
1,000,000,000,000
You can find out more about the British
numbering system at the following website called Numbering Systems
and Place Value:
David M. Schwartz has written a delightful book
called How much is a million? . You can find it in the public
library, and I'm sure you would enjoy it. In his book, he
says:
"How big is a billion? If a billion kids made a
human tower, they would stand up past the moon. If you sat down to
count from one to one billion, you would be counting for 95 years. If
you found a goldfish bowl large enough hold a billion goldfish, it
would be as big as a stadium."
A billion is a difficult number to comprehend, but one advertising
agency did a good job of putting that figure into perspective in one
of its press releases:
A billion seconds ago it was 1959.
A billion minutes ago Jesus was alive.
A billion hours ago our ancestors were living in the Stone
Age.
A billion dollars ago was only 8 hours and 20 minutes, at the rate
Washington spends it.
In today's newspaper, July 6, 1999, to put it
all in perspective, the editorial staff of the Advertiser writes:
"The president just announced that there could
be an extra $1 trillion in the projected federal surplus over the
next 15 years".
How much is a
trillion?
A trillion, in America, is a thousand billion,
which would be written as a one with 12 zeros:
1,000,000,000,000
Mr. Schwartz has this to say about how long it
would take to count to a trillion:
"Since most of the numbers between one and one
trillion are even larger than those on the way to one billion, the
average time required to pronounce them is even longer. Try, for
instance, 369,472,888,227 (three hundred sixty-nine billion, four
hundred seventy-two million, eight hundred eighty-eight thousand, two
hundred twenty-seven). How long did that take you? I would say that
six seconds is an average time per number in counting to a trillion.
(Remember, you have to pronounce every syllable!)
That means it would take six trillion seconds
or 190,259 years to reach the number one trillion - assuming of
course, that modern science discovers the secret of immortality long
before you achieve your goal. (6,000,000,000,000 seconds divided by
60 seconds per minute divided by 60 minutes per hour divided by 24
hours per day divided by 365 days per year = 190,259
years)"
So how much is a trillion dollars? Let's look
at the projected federal surplus. The population of the US is
approximately 250 million. If we divide $1,000,000,000,000 by
250,000,000, we get $4,000. That's $4,000 for each man, woman and
child in the United States. Hope they mail me my check
soon!
Even Bigger
Numbers
Now how about some RIDICULOUSLY big numbers?
Have you ever heard of a googol? Here is a little story from a
fascinating web page by Frank Pilhofer:
"The American mathematician Edward Kasner once
asked his nine-year-old nephew to invent a name for a very large
number, ten to the
and the boy called it a
googol. He thought this was a number to overflow people's minds,
being bigger than anything that can ever be put into words. Another
mathematician then shot back with googolplex, and defined it to be 10
to the power of googol."
Take a look at his web site, at
The following information came from a website
called "Numbering System and Place Values", which you can visit at
the following link:
"One googolplex equals 10 raised to
the
10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000
One googolplex is written as a one followed
by
10,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000
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