C ++ Learning -- container search method (lower_bound, uper_bound)

This article mainly verifies the use of the container search algorithm: lower_bound, uper_bound

Verification item:

1. lower_bound and uper_bound values when key> begin

2. lower_bound and uper_boudn values when key <end

3. When key = a value in the container (not bigin or end), lower_bound and uper_boudn

4. When the key is not equal to any Key in the container, but the ower_bound and uper_boudn values are returned for the key

5. The value when the key is bigin and the key is end

Test code:

# Include "stdafx. h "# include <map >#include <iostream> using namespace std; int _ tmain (int argc, _ TCHAR * argv []) {// lower_bound function usage, this function is used to return the lower bound of the keyword to be searched // upper_bound function usage. This function is used to return the upper bound map <int, string> mp of the keyword to be searched; mp [3] = "3"; mp [4] = "4"; mp [7] = "7"; mp [8] = "8"; map <int, string >:: iterator iterLowerBound5, iterUperBound5; map <int, string >:: iterator iterLowerBound7, struct; map <int, string >:: iterator iterLowerBound3, struct; map <int, string >:: iterator iterLowerBound8, callback; map <int, string >:: iterator iterLowerBound10, iterUperBound10; map <int, string >:: iterator callback, callback; iterLowerBound5 = mp. lower_bound (5); iterUperBound5 = mp. upper_bound (5); iterLowerBound7 = mp. lower_bound (7); iterUperBound7 = mp. upper_bound (7); iterLowerBound3 = mp. lower_bound (0); iterUperBound3 = mp. upper_bound (0); iterLowerBound8 = mp. lower_bound (8); iterUperBound8 = mp. upper_bound (8); iterLowerBound10 = mp. lower_bound (10); iterUperBound10 = mp. upper_bound (10); if (iterLowerBound10 = mp. end () cout <"iterUperBound10 = end" <endl; if (iterUperBound10 = mp. end () cout <"iterUperBound10 = end" <endl; iterLowerBound1 = mp. lower_bound (1); iterUperBound1 = mp. upper_bound (1); if (iterLowerBound1 = mp. end () cout <"iterUperBound1 = end" <endl; if (iterUperBound1 = mp. end () cout <"iterUperBound1 = end" <endl; if (iterLowerBound1 = mp. begin () cout <"iterUperBound1 = begin" <endl; if (iterUperBound1 = mp. begin () cout <"iterUperBound1 = begin" <endl; // iter2 = mp. upper_bound (5); string Str = iterLowerBound5-> second; cout <"lower_bound (5) =" <Str. c_str () <endl; Str = iterUperBound5-> second; cout <"upper_bound (5) =" <Str. c_str () <endl; Str = iterLowerBound7-> second; cout <"lower_bound (7) =" <Str. c_str () <endl; Str = iterUperBound7-> second; cout <"upper_bound (7) =" <Str. c_str () <endl; Str = iterLowerBound3-> second; cout <"lower_bound (0) =" <Str. c_str () <endl; Str = iterUperBound3-> second; cout <"upper_bound (0) =" <Str. c_str () <endl; Str = iterLowerBound8-> second; cout <"lower_bound (8) =" <Str. c_str () <endl; // Str = iterUperBound8-> second; if (iterUperBound8 = mp. end () cout <"upper_bound (8) = end" <Str. c_str () <endl; while (1); return 0 ;}

Print Output:

IterLowerBound10 = end

IterUperBound10 = end

IterLowerBound1 = begin

IterUperBound1 = begin

Lower_bound (5) = 7

Lower_bound (5) = 7

Lower_bound (7) = 7

Lower_bound (7) = 8

Lower_bound (0) = 3

Lower_bound (0) = 3

Lower_bound (8) = 8

Lower_bound (8) = end8

Conclusion:

When the parameter key is not within the container key range:

1. If the value is smaller than the container key uper_bound, lower_bound will return begin.

2. If the value is greater than the container key uper_bound, lower_bound will return the end

When the parameter key is within the container key range:

1. The parameter key = container key. lower_bound will return the iterator of the current key, and uper_bound will return the iterator of the next element.

2. The parameter key is not equal to the container key. In the range, loer_bound returns an iterator that is larger than the parameter key and is adjacent to the container key.

3 if the Key is equal to begin or end, the system returns begin or end.