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Difference between revisions of "cpp/string/basic string/pop back"

From cppreference.com
< cpp‎ | string‎ | basic string
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{{cpp/string/basic_string/title|pop_back}}
 
{{cpp/string/basic_string/title|pop_back}}
 
{{cpp/string/basic_string/navbar}}
 
{{cpp/string/basic_string/navbar}}
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{{ddcl|notes={{mark constexpr since c++20}}|1=
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{{ddcla|constexpr=c++20|
 
void pop_back();
 
void pop_back();
 
}}
 
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{
 
{
 
     std::string str("Short string!");
 
     std::string str("Short string!");
−
     std::cout << "before=" << std::quoted(str) << '\n';
+
     std::cout << "Before: " << std::quoted(str) << '\n';
 
     assert(str.size() == 13);
 
     assert(str.size() == 13);
 
      
 
      
 
     str.pop_back();
 
     str.pop_back();
−
     std::cout << " after=" << std::quoted(str) << '\n';
+
     std::cout << "After:  " << std::quoted(str) << '\n';
 
     assert(str.size() == 12);
 
     assert(str.size() == 12);
 
      
 
      
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}
 
}
 
|output=
 
|output=
−
before="Short string!"
+
Before: "Short string!"
−
  after="Short string"
+
After: "Short string"
 
}}
 
}}
  

Latest revision as of 14:10, 18 October 2024

 
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void pop_back();
 (constexpr since C++20)

Removes the last character from the string.

Equivalent to erase(end() - 1). The behavior is undefined if the string is empty.

Contents

[edit] Parameters

(none)

[edit] Return value

(none)

[edit] Complexity

Constant.

[edit] Exceptions

Throws nothing.

[edit] Notes

In libstdc++, pop_back() is not available in C++98 mode.

[edit] Example

Run this code
#include <cassert>
#include <iomanip>
#include <iostream>
#include <string>
 
int main()
{
    std::string str("Short string!");
    std::cout << "Before: " << std::quoted(str) << '\n';
    assert(str.size() == 13);
 
    str.pop_back();
    std::cout << "After:  " << std::quoted(str) << '\n';
    assert(str.size() == 12);
 
    str.clear();
//  str.pop_back(); // undefined behavior
}

Output: 

Before: "Short string!"
After:  "Short string"

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 534 C++98 std::basic_string did not have the member function pop_back() added

[edit] See also

 appends a character to the end
(public member function) [edit]
removes characters
(public member function) [edit]
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