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@@ -148,4 +148,4 @@
|
||||
<span class=w> </span><span class=n>std</span><span class=o>::</span><span class=n>cout</span><span class=w> </span><span class=o><<</span><span class=w> </span><span class=n>j_array</span><span class=w> </span><span class=o><<</span><span class=w> </span><span class=sc>'\n'</span><span class=p>;</span>
|
||||
<span class=p>}</span>
|
||||
</code></pre></div> <p>Output:</p> <div class=highlight><pre><span></span><code><span class=p>[</span><span class=mi>0</span><span class=p>,</span><span class=mi>1</span><span class=p>,</span><span class=mi>3</span><span class=p>,</span><span class=mi>4</span><span class=p>,</span><span class=mi>5</span><span class=p>]</span>
|
||||
</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">¶</a></h2> <ul> <li><a href=../clear/ >clear</a> clears the contents</li> <li><a href=../insert/ >insert</a> add values to an array/object</li> <li><a href=../../../features/modifying_values/ >Modifying values</a> - the article on modifying values</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">¶</a></h2> <ol> <li>Added in version 1.0.0. Added support for binary types in version 3.8.0.</li> <li>Added in version 1.0.0. Added support for binary types in version 3.8.0.</li> <li>Added in version 1.0.0.</li> <li>Added in version 3.11.0.</li> <li>Added in version 1.0.0.</li> </ol> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="July 4, 2026 09:13:25 UTC">July 4, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright © 2013-2026 Niels Lohmann </div> </div> <div class=md-social> <a href="https://github.com/nlohmann" target="_blank" rel="noopener" title="github.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 512 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M173.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6m-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3m44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9M252.8 8C114.1 8 8 113.3 8 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C436.2 457.8 504 362.9 504 252 504 113.3 391.5 8 252.8 8M105.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1m-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7m32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1m-11.4-14.7c-1.6 1-1.6 3.6 0 5.9s4.3 3.3 5.6 2.3c1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2"/></svg> </a> <a href="https://www.linkedin.com/in/nielslohmann/" target="_blank" rel="noopener" title="www.linkedin.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 448 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M416 32H31.9C14.3 32 0 46.5 0 64.3v383.4C0 465.5 14.3 480 31.9 480H416c17.6 0 32-14.5 32-32.3V64.3c0-17.8-14.4-32.3-32-32.3M135.4 416H69V202.2h66.5V416zM102.2 96a38.5 38.5 0 1 1 0 77 38.5 38.5 0 1 1 0-77m282.1 320h-66.4V312c0-24.8-.5-56.7-34.5-56.7-34.6 0-39.9 27-39.9 54.9V416h-66.4V202.2h63.7v29.2h.9c8.9-16.8 30.6-34.5 62.9-34.5 67.2 0 79.7 44.3 Line truncated
|
||||
</code></pre></div> </details> <h2 id=see-also>See also<a class=headerlink href=#see-also title="Permanent link">¶</a></h2> <ul> <li><a href=../clear/ >clear</a> clears the contents</li> <li><a href=../insert/ >insert</a> add values to an array/object</li> <li><a href=../../../features/modifying_values/ >Modifying values</a> - the article on modifying values</li> </ul> <h2 id=version-history>Version history<a class=headerlink href=#version-history title="Permanent link">¶</a></h2> <ol> <li>Added in version 1.0.0. Added support for binary types in version 3.8.0.</li> <li>Added in version 1.0.0. Added support for binary types in version 3.8.0.</li> <li>Added in version 1.0.0.</li> <li>Added in version 3.11.0.</li> <li>Added in version 1.0.0.</li> </ol> <!-- https://squidfunk.github.io/mkdocs-material/reference/tooltips/#adding-a-glossary --> <aside class=md-source-file> <span class=md-source-file__fact> <span class=md-icon title="Last update"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M21 13.1c-.1 0-.3.1-.4.2l-1 1 2.1 2.1 1-1c.2-.2.2-.6 0-.8l-1.3-1.3c-.1-.1-.2-.2-.4-.2m-1.9 1.8-6.1 6V23h2.1l6.1-6.1zM12.5 7v5.2l4 2.4-1 1L11 13V7zM11 21.9c-5.1-.5-9-4.8-9-9.9C2 6.5 6.5 2 12 2c5.3 0 9.6 4.1 10 9.3-.3-.1-.6-.2-1-.2s-.7.1-1 .2C19.6 7.2 16.2 4 12 4c-4.4 0-8 3.6-8 8 0 4.1 3.1 7.5 7.1 7.9l-.1.2z"/></svg> </span> <span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date" title="July 8, 2026 18:18:24 UTC">July 8, 2026</span> </span> </aside> </article> </div> <script>var tabs=__md_get("__tabs");if(Array.isArray(tabs))e:for(var set of document.querySelectorAll(".tabbed-set")){var labels=set.querySelector(".tabbed-labels");for(var tab of tabs)for(var label of labels.getElementsByTagName("label"))if(label.innerText.trim()===tab){var input=document.getElementById(label.htmlFor);input.checked=!0;continue e}}</script> <script>var target=document.getElementById(location.hash.slice(1));target&&target.name&&(target.checked=target.name.startsWith("__tabbed_"))</script> </div> <button type=button class="md-top md-icon" data-md-component=top hidden> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 24 24"><path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8z"/></svg> Back to top </button> </main> <footer class=md-footer> <div class="md-footer-meta md-typeset"> <div class="md-footer-meta__inner md-grid"> <div class=md-copyright> <div class=md-copyright__highlight> Copyright © 2013-2026 Niels Lohmann </div> </div> <div class=md-social> <a href="https://github.com/nlohmann" target="_blank" rel="noopener" title="github.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 512 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M173.9 397.4c0 2-2.3 3.6-5.2 3.6-3.3.3-5.6-1.3-5.6-3.6 0-2 2.3-3.6 5.2-3.6 3-.3 5.6 1.3 5.6 3.6m-31.1-4.5c-.7 2 1.3 4.3 4.3 4.9 2.6 1 5.6 0 6.2-2s-1.3-4.3-4.3-5.2c-2.6-.7-5.5.3-6.2 2.3m44.2-1.7c-2.9.7-4.9 2.6-4.6 4.9.3 2 2.9 3.3 5.9 2.6 2.9-.7 4.9-2.6 4.6-4.6-.3-1.9-3-3.2-5.9-2.9M252.8 8C114.1 8 8 113.3 8 252c0 110.9 69.8 205.8 169.5 239.2 12.8 2.3 17.3-5.6 17.3-12.1 0-6.2-.3-40.4-.3-61.4 0 0-70 15-84.7-29.8 0 0-11.4-29.1-27.8-36.6 0 0-22.9-15.7 1.6-15.4 0 0 24.9 2 38.6 25.8 21.9 38.6 58.6 27.5 72.9 20.9 2.3-16 8.8-27.1 16-33.7-55.9-6.2-112.3-14.3-112.3-110.5 0-27.5 7.6-41.3 23.6-58.9-2.6-6.5-11.1-33.3 2.6-67.9 20.9-6.5 69 27 69 27 20-5.6 41.5-8.5 62.8-8.5s42.8 2.9 62.8 8.5c0 0 48.1-33.6 69-27 13.7 34.7 5.2 61.4 2.6 67.9 16 17.7 25.8 31.5 25.8 58.9 0 96.5-58.9 104.2-114.8 110.5 9.2 7.9 17 22.9 17 46.4 0 33.7-.3 75.4-.3 83.6 0 6.5 4.6 14.4 17.3 12.1C436.2 457.8 504 362.9 504 252 504 113.3 391.5 8 252.8 8M105.2 352.9c-1.3 1-1 3.3.7 5.2 1.6 1.6 3.9 2.3 5.2 1 1.3-1 1-3.3-.7-5.2-1.6-1.6-3.9-2.3-5.2-1m-10.8-8.1c-.7 1.3.3 2.9 2.3 3.9 1.6 1 3.6.7 4.3-.7.7-1.3-.3-2.9-2.3-3.9-2-.6-3.6-.3-4.3.7m32.4 35.6c-1.6 1.3-1 4.3 1.3 6.2 2.3 2.3 5.2 2.6 6.5 1 1.3-1.3.7-4.3-1.3-6.2-2.2-2.3-5.2-2.6-6.5-1m-11.4-14.7c-1.6 1-1.6 3.6 0 5.9s4.3 3.3 5.6 2.3c1.6-1.3 1.6-3.9 0-6.2-1.4-2.3-4-3.3-5.6-2"/></svg> </a> <a href="https://www.linkedin.com/in/nielslohmann/" target="_blank" rel="noopener" title="www.linkedin.com" class="md-social__link"> <svg xmlns=http://www.w3.org/2000/svg viewbox="0 0 448 512"><!-- Font Awesome Free 7.1.0 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2025 Fonticons, Inc.--><path d="M416 32H31.9C14.3 32 0 46.5 0 64.3v383.4C0 465.5 14.3 480 31.9 480H416c17.6 0 32-14.5 32-32.3V64.3c0-17.8-14.4-32.3-32-32.3M135.4 416H69V202.2h66.5V416zM102.2 96a38.5 38.5 0 1 1 0 77 38.5 38.5 0 1 1 0-77m282.1 320h-66.4V312c0-24.8-.5-56.7-34.5-56.7-34.6 0-39.9 27-39.9 54.9V416h-66.4V202.2h63.7v29.2h.9c8.9-16.8 30.6-34.5 62.9-34.5 67.2 0 79.7 44.3 Line truncated
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@@ -0,0 +1,313 @@
|
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# nlohmann::basic_json::erase
|
||||
|
||||
```
|
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// (1)
|
||||
iterator erase(iterator pos);
|
||||
const_iterator erase(const_iterator pos);
|
||||
|
||||
// (2)
|
||||
iterator erase(iterator first, iterator last);
|
||||
const_iterator erase(const_iterator first, const_iterator last);
|
||||
|
||||
// (3)
|
||||
size_type erase(const typename object_t::key_type& key);
|
||||
|
||||
// (4)
|
||||
template<typename KeyType>
|
||||
size_type erase(KeyType&& key);
|
||||
|
||||
// (5)
|
||||
void erase(const size_type idx);
|
||||
```
|
||||
|
||||
1. Removes an element from a JSON value specified by iterator `pos`. The iterator `pos` must be valid and dereferenceable. Thus, the `end()` iterator (which is valid, but is not dereferenceable) cannot be used as a value for `pos`.
|
||||
|
||||
If called on a primitive type other than `null`, the resulting JSON value will be `null`.
|
||||
|
||||
1. Remove an element range specified by `[first; last)` from a JSON value. The iterator `first` does not need to be dereferenceable if `first == last`: erasing an empty range is a no-op.
|
||||
|
||||
If called on a primitive type other than `null`, the resulting JSON value will be `null`.
|
||||
|
||||
1. Removes an element from a JSON object by key.
|
||||
|
||||
1. See 3. This overload is only available if `KeyType` is comparable with `typename object_t::key_type` and `typename object_comparator_t::is_transparent` denotes a type.
|
||||
|
||||
1. Removes an element from a JSON array by index.
|
||||
|
||||
## Template parameters
|
||||
|
||||
`KeyType` : A type for an object key other than [`json_pointer`](https://json.nlohmann.me/api/json_pointer/index.md) that is comparable with [`string_t`](https://json.nlohmann.me/api/basic_json/string_t/index.md) using [`object_comparator_t`](https://json.nlohmann.me/api/basic_json/object_comparator_t/index.md). This can also be a string view (C++17).
|
||||
|
||||
## Parameters
|
||||
|
||||
`pos` (in) : iterator to the element to remove
|
||||
|
||||
`first` (in) : iterator to the beginning of the range to remove
|
||||
|
||||
`last` (in) : iterator past the end of the range to remove
|
||||
|
||||
`key` (in) : object key of the elements to remove
|
||||
|
||||
`idx` (in) : array index of the element to remove
|
||||
|
||||
## Return value
|
||||
|
||||
1. Iterator following the last removed element. If the iterator `pos` refers to the last element, the `end()` iterator is returned.
|
||||
1. Iterator following the last removed element. If the iterator `last` refers to the last element, the `end()` iterator is returned.
|
||||
1. Number of elements removed. If `ObjectType` is the default `std::map` type, the return value will always be `0` (`key` was not found) or `1` (`key` was found).
|
||||
1. See 3.
|
||||
1. (none)
|
||||
|
||||
## Exception safety
|
||||
|
||||
Strong exception safety: if an exception occurs, the original value stays intact.
|
||||
|
||||
## Exceptions
|
||||
|
||||
1. The function can throw the following exceptions:
|
||||
- Throws [`type_error.307`](https://json.nlohmann.me/home/exceptions/#jsonexceptiontype_error307) if called on a `null` value; example: `"cannot use erase() with null"`
|
||||
- Throws [`invalid_iterator.202`](https://json.nlohmann.me/home/exceptions/#jsonexceptioninvalid_iterator202) if called on an iterator which does not belong to the current JSON value; example: `"iterator does not fit current value"`
|
||||
- Throws [`invalid_iterator.205`](https://json.nlohmann.me/home/exceptions/#jsonexceptioninvalid_iterator205) if called on a primitive type with invalid iterator (i.e., any iterator which is not `begin()`); example: `"iterator out of range"`
|
||||
1. The function can throw the following exceptions:
|
||||
- Throws [`type_error.307`](https://json.nlohmann.me/home/exceptions/#jsonexceptiontype_error307) if called on a `null` value; example: `"cannot use erase() with null"`
|
||||
- Throws [`invalid_iterator.203`](https://json.nlohmann.me/home/exceptions/#jsonexceptioninvalid_iterator203) if called on iterators which does not belong to the current JSON value; example: `"iterators do not fit current value"`
|
||||
- Throws [`invalid_iterator.204`](https://json.nlohmann.me/home/exceptions/#jsonexceptioninvalid_iterator204) if called on a primitive type with invalid iterators (i.e., if `first != begin()` and `last != end()`); example: `"iterators out of range"`
|
||||
1. The function can throw the following exceptions:
|
||||
- Throws [`type_error.307`](https://json.nlohmann.me/home/exceptions/#jsonexceptiontype_error307) when called on a type other than JSON object; example: `"cannot use erase() with null"`
|
||||
1. See 3.
|
||||
1. The function can throw the following exceptions:
|
||||
- Throws [`type_error.307`](https://json.nlohmann.me/home/exceptions/#jsonexceptiontype_error307) when called on a type other than JSON array; example: `"cannot use erase() with null"`
|
||||
- Throws [`out_of_range.401`](https://json.nlohmann.me/home/exceptions/#jsonexceptionout_of_range401) when `idx >= size()`; example: `"array index 17 is out of range"`
|
||||
|
||||
## Complexity
|
||||
|
||||
1. The complexity depends on the type:
|
||||
- objects: amortized constant
|
||||
- arrays: linear in distance between `pos` and the end of the container
|
||||
- strings and binary: linear in the length of the member
|
||||
- other types: constant
|
||||
1. The complexity depends on the type:
|
||||
- objects: `log(size()) + std::distance(first, last)`
|
||||
- arrays: linear in the distance between `first` and `last`, plus linear in the distance between `last` and end of the container
|
||||
- strings and binary: linear in the length of the member
|
||||
- other types: constant
|
||||
1. `log(size()) + count(key)`
|
||||
1. `log(size()) + count(key)`
|
||||
1. Linear in distance between `idx` and the end of the container.
|
||||
|
||||
## Notes
|
||||
|
||||
1. Invalidates iterators and references at or after the point of the `erase`, including the `end()` iterator.
|
||||
1. (none)
|
||||
1. References and iterators to the erased elements are invalidated. Other references and iterators are not affected.
|
||||
1. See 3.
|
||||
1. (none)
|
||||
|
||||
## Examples
|
||||
|
||||
Example: (1) remove element given an iterator
|
||||
|
||||
The example shows the effect of `erase()` for different JSON types using an iterator.
|
||||
|
||||
```
|
||||
#include <iostream>
|
||||
#include <nlohmann/json.hpp>
|
||||
|
||||
using json = nlohmann::json;
|
||||
|
||||
int main()
|
||||
{
|
||||
// create JSON values
|
||||
json j_boolean = true;
|
||||
json j_number_integer = 17;
|
||||
json j_number_float = 23.42;
|
||||
json j_object = {{"one", 1}, {"two", 2}};
|
||||
json j_array = {1, 2, 4, 8, 16};
|
||||
json j_string = "Hello, world";
|
||||
|
||||
// call erase()
|
||||
j_boolean.erase(j_boolean.begin());
|
||||
j_number_integer.erase(j_number_integer.begin());
|
||||
j_number_float.erase(j_number_float.begin());
|
||||
j_object.erase(j_object.find("two"));
|
||||
j_array.erase(j_array.begin() + 2);
|
||||
j_string.erase(j_string.begin());
|
||||
|
||||
// print values
|
||||
std::cout << j_boolean << '\n';
|
||||
std::cout << j_number_integer << '\n';
|
||||
std::cout << j_number_float << '\n';
|
||||
std::cout << j_object << '\n';
|
||||
std::cout << j_array << '\n';
|
||||
std::cout << j_string << '\n';
|
||||
}
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```
|
||||
null
|
||||
null
|
||||
null
|
||||
{"one":1}
|
||||
[1,2,8,16]
|
||||
null
|
||||
```
|
||||
|
||||
Example: (2) remove elements given an iterator range
|
||||
|
||||
The example shows the effect of `erase()` for different JSON types using an iterator range.
|
||||
|
||||
```
|
||||
#include <iostream>
|
||||
#include <nlohmann/json.hpp>
|
||||
|
||||
using json = nlohmann::json;
|
||||
|
||||
int main()
|
||||
{
|
||||
// create JSON values
|
||||
json j_boolean = true;
|
||||
json j_number_integer = 17;
|
||||
json j_number_float = 23.42;
|
||||
json j_object = {{"one", 1}, {"two", 2}};
|
||||
json j_array = {1, 2, 4, 8, 16};
|
||||
json j_string = "Hello, world";
|
||||
|
||||
// call erase()
|
||||
j_boolean.erase(j_boolean.begin(), j_boolean.end());
|
||||
j_number_integer.erase(j_number_integer.begin(), j_number_integer.end());
|
||||
j_number_float.erase(j_number_float.begin(), j_number_float.end());
|
||||
j_object.erase(j_object.find("two"), j_object.end());
|
||||
j_array.erase(j_array.begin() + 1, j_array.begin() + 3);
|
||||
j_string.erase(j_string.begin(), j_string.end());
|
||||
|
||||
// print values
|
||||
std::cout << j_boolean << '\n';
|
||||
std::cout << j_number_integer << '\n';
|
||||
std::cout << j_number_float << '\n';
|
||||
std::cout << j_object << '\n';
|
||||
std::cout << j_array << '\n';
|
||||
std::cout << j_string << '\n';
|
||||
}
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```
|
||||
null
|
||||
null
|
||||
null
|
||||
{"one":1}
|
||||
[1,8,16]
|
||||
null
|
||||
```
|
||||
|
||||
Example: (3) remove element from a JSON object given a key
|
||||
|
||||
The example shows the effect of `erase()` for different JSON types using an object key.
|
||||
|
||||
```
|
||||
#include <iostream>
|
||||
#include <nlohmann/json.hpp>
|
||||
|
||||
using json = nlohmann::json;
|
||||
|
||||
int main()
|
||||
{
|
||||
// create a JSON object
|
||||
json j_object = {{"one", 1}, {"two", 2}};
|
||||
|
||||
// call erase()
|
||||
auto count_one = j_object.erase("one");
|
||||
auto count_three = j_object.erase("three");
|
||||
|
||||
// print values
|
||||
std::cout << j_object << '\n';
|
||||
std::cout << count_one << " " << count_three << '\n';
|
||||
}
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```
|
||||
{"two":2}
|
||||
1 0
|
||||
```
|
||||
|
||||
Example: (4) remove element from a JSON object given a key using string_view
|
||||
|
||||
The example shows the effect of `erase()` for different JSON types using an object key.
|
||||
|
||||
```
|
||||
#include <iostream>
|
||||
#include <string_view>
|
||||
#include <nlohmann/json.hpp>
|
||||
|
||||
using namespace std::string_view_literals;
|
||||
using json = nlohmann::json;
|
||||
|
||||
int main()
|
||||
{
|
||||
// create a JSON object
|
||||
json j_object = {{"one", 1}, {"two", 2}};
|
||||
|
||||
// call erase()
|
||||
auto count_one = j_object.erase("one"sv);
|
||||
auto count_three = j_object.erase("three"sv);
|
||||
|
||||
// print values
|
||||
std::cout << j_object << '\n';
|
||||
std::cout << count_one << " " << count_three << '\n';
|
||||
}
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```
|
||||
{"two":2}
|
||||
1 0
|
||||
```
|
||||
|
||||
Example: (5) remove element from a JSON array given an index
|
||||
|
||||
The example shows the effect of `erase()` using an array index.
|
||||
|
||||
```
|
||||
#include <iostream>
|
||||
#include <nlohmann/json.hpp>
|
||||
|
||||
using json = nlohmann::json;
|
||||
|
||||
int main()
|
||||
{
|
||||
// create a JSON array
|
||||
json j_array = {0, 1, 2, 3, 4, 5};
|
||||
|
||||
// call erase()
|
||||
j_array.erase(2);
|
||||
|
||||
// print values
|
||||
std::cout << j_array << '\n';
|
||||
}
|
||||
```
|
||||
|
||||
Output:
|
||||
|
||||
```
|
||||
[0,1,3,4,5]
|
||||
```
|
||||
|
||||
## See also
|
||||
|
||||
- [clear](https://json.nlohmann.me/api/basic_json/clear/index.md) clears the contents
|
||||
- [insert](https://json.nlohmann.me/api/basic_json/insert/index.md) add values to an array/object
|
||||
- [Modifying values](https://json.nlohmann.me/features/modifying_values/index.md) - the article on modifying values
|
||||
|
||||
## Version history
|
||||
|
||||
1. Added in version 1.0.0. Added support for binary types in version 3.8.0.
|
||||
1. Added in version 1.0.0. Added support for binary types in version 3.8.0.
|
||||
1. Added in version 1.0.0.
|
||||
1. Added in version 3.11.0.
|
||||
1. Added in version 1.0.0.
|
||||
Reference in new issue
Block a user