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:
[Cpp]
# 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 of the keyword to be searched.
Map <int, string> mp;
 
Mp [3] = "3 ";
Mp [4] = "4 ";
Mp [7] = "7 ";
Mp [8] = "8 ";
 
Map <int, string >:: iterator iterLowerBound5, iterUperBound5;
Map <int, string >:: iterator iterLowerBound7, iterUperBound7;
Map <int, string >:: iterator iterLowerBound3, iterUperBound3;
Map <int, string >:: iterator iterLowerBound8, iterUperBound8;
Map <int, string >:: iterator iterLowerBound10, iterUperBound10;
Map <int, string >:: iterator iterLowerBound1, iterUperBound1;
 
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.

 

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