【常用技巧】C++ STL容器操作:6种常用场景算法

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简介: STL在Linux C++中使用的非常普遍,掌握并合适的使用各种容器至关重要!

C++ STL容器操作:6种常用场景算法

引言

  在日常软件开发工作中,容器操作如查找、排序、和元素替换等任务极为常见。幸运的是,C++的标准化利器——STL(Standard Template Library,标准模板库)为我们封装了一系列高效且灵活的算法,极大简化了这些操作。特别是自C++11版本以来,STL引入了一批新晋的通用算法,它们不仅功能强大,而且设计得更加人性化,旨在进一步提升我们的编码效率与程序性能。本文列举一些常用到的方法,便于日后回顾和查阅。

概述

  日常开发中的容器操作,如查找、删除、排序、分割、拷贝和合并,均可借助STL中的精选算法高效完成。本文将概览这些核心STL算法,助力开发流程优化。

查找与计数

std::find

  • 作用: 找容器中第一个匹配给定值的元素
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
      DumpVector("testArrgs", testArrgs);
    
      auto find = std::find(testArrgs.begin(), testArrgs.end(), "XiaoMing");
      if (find != testArrgs.end()) {
          SPR_LOGD("find: dest = \"XiaoMing\", result = %s, index = %ld\n", find->c_str(), find - testArrgs.begin());
      }
    
  • 结果
    D: find: dest = "XiaoMing", result = XiaoMing, index = 2
    

std::find_if

  • 作用: 查找容器中第一个满足谓词条件的元素
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      auto findIf = std::find_if(testArrgs.begin(), testArrgs.end(),  [](const std::string &str) { return str.find("Ming") != std::string::npos; });
      if (findIf != testArrgs.end()) {
          SPR_LOGD("find_if: dest = \"Ming\", result = %s, index = %ld\n", findIf->c_str(), findIf - testArrgs.begin());
      }
    

    ③ 结果

    D: find_if: dest = "Ming", result = XiaoMing, index = 2
    

std::find_if_not

  • 作用: 寻找第一个不符合指定条件的元素
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      auto findIfNot = std::find_if_not(testArrgs.begin(), testArrgs.end(),  [](const std::string &str) { return str.find("Xiao") != std::string::npos; });
      if (findIfNot != testArrgs.end()) {
          SPR_LOGD("find_if_not: dest = \"Xiao\", result = %s, index = %ld\n", findIfNot->c_str(), findIfNot - testArrgs.begin());
      }
    
  • 结果
    D: find_if_not: dest = "Xiao", result = LiHua, index = 1
    

std::find_end

  • 作用: 查找一个子序列最后一次出现的位置
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> subArrgs1 = {"XiaoMing", "XiaoHong"};
      auto findEnd = std::find_end(testArrgs.begin(), testArrgs.end(), subArrgs1.begin(), subArrgs1.end());
      if (findEnd != testArrgs.end()) {
          SPR_LOGD("find_end: dest = {\"XiaoMing\", \"XiaoHong\"}, result = %s, index = %ld\n", findEnd->c_str(), findEnd - testArrgs.begin());
      }
    
  • 结果
    D: find_end: dest = {"XiaoMing", "XiaoHong"}, result = XiaoMing, index = 3
    

std::find_first_of

  • 作用: 查找序列中任何一个元素首次出现的位置
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> subArrgs2 = {"JianGuo"};
      auto findFirstOf = std::find_first_of(testArrgs.begin(), testArrgs.end(), subArrgs2.begin(), subArrgs2.end());
      if (findFirstOf != testArrgs.end()) {
          SPR_LOGD("find_first_of: dest = {\"JianGuo\"}, result = %s, index = %ld\n", findFirstOf->c_str(), findFirstOf - testArrgs.begin());
      }
    
  • 结果
    D: find_first_of: dest = {"JianGuo"}, result = JianGuo, index = 5
    

std::adjacent_find

  • 作用: 查找相邻重复的元素
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      auto adjacentFind = std::adjacent_find(testArrgs.begin(), testArrgs.end(), [](const std::string &str1, const std::string &str2) { return str1 == str2; });
      if (adjacentFind != testArrgs.end()) {
          SPR_LOGD("adjacent_find: result = %s, index = %ld\n", adjacentFind->c_str(), adjacentFind - testArrgs.begin());
      }
    
  • 结果
    D: adjacent_find: result = XiaoMing, index = 2
    

std::count

  • 作用: 计算容器中指定值出现的次数
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      auto cnt = std::count(testArrgs.begin(), testArrgs.end(), "XiaoFang");
      if (cnt > 0) {
          SPR_LOGD("count: dest = \"XiaoFang\", result = %ld\n", cnt);
      }
    
  • 结果
    D: count: dest = "XiaoFang", result = 1
    

std::count_if

  • 作用: 计算满足谓词条件的元素数量
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      auto cntIf = std::count_if(testArrgs.begin(), testArrgs.end(), [](const std::string &str) { return str.find("Xiao") != std::string::npos; });
      if (cntIf > 0) {
          SPR_LOGD("count_if: dest = \"Xiao\", result = %ld\n", cntIf);
      }
    
  • 结果
    D: count_if: dest = "Xiao", result = 6
    

移除与替换

std::remove

  • 作用: 重新排列容器元素,使得所有不匹配特定值的元素被放置在容器的前端。配合earse实现移除不匹配元素。
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> rmArrgs(testArrgs);
      auto remove = std::remove(rmArrgs.begin(), rmArrgs.end(), "XiaoMing");
      if (remove != rmArrgs.end()) {
          rmArrgs.erase(remove, rmArrgs.end());
          DumpVector("rmArrgs", rmArrgs);
      }
    
  • 结果
    D: rmArrgs: "XiaoFang", "LiHua", "XiaoHong", "JianGuo", "XiaoFangFang",
    

std::remove_if

  • 作用: 重新排列容器元素,使得所有不满足谓词条件的元素被放置在容器的前端。配合earse实现移除不匹配元素。
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> rmIfArrgs(testArrgs);
      auto removeIf = std::remove_if(rmIfArrgs.begin(), rmIfArrgs.end(), [](const std::string &str) { return str.find("Xiao") != std::string::npos; });
      if (removeIf != rmIfArrgs.end()) {
          rmIfArrgs.erase(removeIf, rmIfArrgs.end());
          DumpVector("rmArrgs", rmArrgs);
      }
    
  • 结果
    D: rmIfArrgs: "XiaoFang", "LiHua", "XiaoHong", "JianGuo", "XiaoFangFang"
    

std::remove_copy

  • 作用: 从源序列拷贝元素到目标序列,排除满足条件的元素。
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> dstArrgs;
      vector<std::string> rcArrgs(testArrgs);
      std::remove_copy(rcArrgs.begin(), rcArrgs.end(), std::back_inserter(dstArrgs), "XiaoMing");
      DumpVector("dstArrgs", dstArrgs);
    
  • 结果
    D: dstArrgs: "XiaoFang", "LiHua", "XiaoHong", "JianGuo", "XiaoFangFang"
    

std::replace

  • 作用: 将所有出现的指定元素替换为新值。
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> rpArrgs(testArrgs);
      std::replace(rpArrgs.begin(), rpArrgs.end(), "XiaoMing", "MingMing");
      DumpVector("rpArrgs", rpArrgs);
    
  • 结果
    D: rpArrgs: "XiaoFang", "LiHua", "MingMing", "MingMing", "XiaoHong", "JianGuo", "XiaoFangFang", "MingMing",
    

std::replace_if

  • 作用: 满足谓词条件的元素,替换为指定的替换值。
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> rpIfArrgs(testArrgs);
      std::replace_if(rpIfArrgs.begin(), rpIfArrgs.end(), [](const std::string &str) { return (str == "XiaoFang"); }, "FangFang");
      DumpVector("rpIfArrgs", rpIfArrgs);
    
  • 结果
    D: rpIfArrgs: "FangFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing",
    

std::replace_copy

  • 作用:用于在指定范围内将所有匹配某个值的元素替换为另一个值,拷贝到另一个的容器中。
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> rpCpDstArrgs;
      vector<std::string> rpCopyArrgs(testArrgs);
      std::replace_copy(rpCopyArrgs.begin(), rpCopyArrgs.end(), std::back_inserter(rpCpDstArrgs), "XiaoMing", "MingMing");
      DumpVector("rpCpDstArrgs", rpCpDstArrgs);
    
  • 结果
    D: rpCpDstArrgs: "XiaoFang", "LiHua", "MingMing", "MingMing", "XiaoHong", "JianGuo", "XiaoFangFang", "MingMing"
    

std::swap

  • 作用:交换两个变量的值。
  • 示例

      vector<std::string> testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};
    
      vector<std::string> swapSrcArrgs(testArrgs);
      vector<std::string> swapDstArrgs = {"Vince Carter", "Rose", "James"};
      std::swap(swapSrcArrgs, swapDstArrgs);
      DumpVector("swapSrcArrgs", swapSrcArrgs);
      DumpVector("swapDstArrgs", swapDstArrgs);
    
  • 结果
    D: swapSrcArrgs: "Vince Carter", "Rose", "James", 
    D: swapDstArrgs: "XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing",
    

排序与组织

std::sort

  • 作用:对容器元素进行排序。
  • 示例
    ```c++
    vector testArrgs = {"XiaoFang", "LiHua", "XiaoMing", "XiaoMing", "XiaoHong", "JianGuo", "XiaoFangFang", "XiaoMing"};

    // sort
    vector sortArrgs(testArrgs);
    std::sort(sortArrgs.begin(), sortArrgs.end());
    DumpVector("sortArrgs", sortArrgs);
    std::sort(sortArrgs.begin(), sortArrgs.end(), { return str1.size() > str2.size(); });
    DumpVector("sortArrgs", sortArrgs);

* 结果
```c++
  D: sortArrgs: "JianGuo", "LiHua", "XiaoFang", "XiaoFangFang", "XiaoHong", "XiaoMing", "XiaoMing", "XiaoMing", 
  D: sortArrgs: "XiaoFangFang", "XiaoFang", "XiaoHong", "XiaoMing", "XiaoMing", "XiaoMing", "JianGuo", "LiHua",

std::stable_sort

  • 作用:稳定排序,保持相等元素的原有顺序。
  • 示例
      // stable_sort
      vector<Persion> srcPersions = {
        {"LiWei", 18}, {"LiHua", 20}, {"ZhangLei", 19}, {"WeiGuo", 19}, {"ZhenHua", 20}, {"JianGuo", 18}, {"ZhiGuo", 19}, {"JianHua", 19}};
      vector<Persion> sPersions(srcPersions);
      std::stable_sort(sPersions.begin(), sPersions.end(), [](const Persion &p1, const Persion &p2) { return p1.age > p2.age; });
      DumpVector("sPersions", sPersions);
      std::stable_sort(sPersions.begin(), sPersions.end(), [](const Persion &p1, const Persion &p2) { return p1.age < p2.age; });
      DumpVector("sPersions", sPersions);
    
  • 结果
    D: sPersions = { {"LiHua", 20}, {"ZhenHua", 20}, {"ZhangLei", 19}, {"WeiGuo", 19}, {"ZhiGuo", 19}, {"JianHua", 19}, {"LiWei", 18}, {"JianGuo", 18}, }
    D: sPersions = { {"LiWei", 18}, {"JianGuo", 18}, {"ZhangLei", 19}, {"WeiGuo", 19}, {"ZhiGuo", 19}, {"JianHua", 19}, {"LiHua", 20}, {"ZhenHua", 20}, }
    

std::partial_sort

  • 作用:对部分区间排序。
  • 示例

      vector<Persion> srcPersions = {
        {"LiWei", 18}, {"LiHua", 20}, {"ZhangLei", 19}, {"WeiGuo", 19}, {"ZhenHua", 20}, {"JianGuo", 18}, {"ZhiGuo", 19}, {"JianHua", 19}};
    
      // partial_sort
      vector<Persion> prtPersions(srcPersions);
      vector<Persion> sortPersions(srcPersions);
      std::partial_sort(prtPersions.begin(), prtPersions.begin() + 5, prtPersions.end(), [](const Persion &p1, const Persion &p2) { return p1.age > p2.age; });
      std::sort(sortPersions.begin(), sortPersions.begin() + 5, [](const Persion &p1, const Persion &p2) { return p1.age > p2.age; });
      DumpVector("prtPersions", prtPersions);
      DumpVector("sortPersions", sortPersions);
    
  • 结果
    D: prtPersions = { {"ZhenHua", 20}, {"LiHua", 20}, {"WeiGuo", 19}, {"ZhiGuo", 19}, {"ZhangLei", 19}, {"JianGuo", 18}, {"LiWei", 18}, {"JianHua", 19}, }
    D: sortPersions = { {"LiHua", 20}, {"ZhenHua", 20}, {"ZhangLei", 19}, {"WeiGuo", 19}, {"LiWei", 18}, {"JianGuo", 18}, {"ZhiGuo", 19}, {"JianHua", 19}, }
    

std::reverse

  • 作用:对部分区间排序。
  • 示例

      vector<Persion> srcPersions = {
        {"LiWei", 18}, {"LiHua", 20}, {"ZhangLei", 19}, {"WeiGuo", 19}, {"ZhenHua", 20}, {"JianGuo", 18}, {"ZhiGuo", 19}, {"JianHua", 19}};
    
      // reverse
      vector<Persion> rPersions(srcPersions);
      std::reverse(rPersions.begin(), rPersions.end());
      DumpVector("rPersions", rPersions);
    
  • 结果
    D: rPersions = { {"JianHua", 19}, {"ZhiGuo", 19}, {"JianGuo", 18}, {"ZhenHua", 20}, {"WeiGuo", 19}, {"ZhangLei", 19}, {"LiHua", 20}, {"LiWei", 18}, }
    

std::rotate

  • 作用:对部分区间排序。
  • 示例

      vector<Persion> srcPersions = {
        {"LiWei", 18}, {"LiHua", 20}, {"ZhangLei", 19}, {"WeiGuo", 19}, {"ZhenHua", 20}, {"JianGuo", 18}, {"ZhiGuo", 19}, {"JianHua", 19}};
    
      // rotate
      vector<Persion> rtPersions(srcPersions);
      std::rotate(rtPersions.begin(), rtPersions.begin() + 3, rtPersions.end());
      DumpVector("rtPersions", rtPersions);
    
  • 结果
    D: rPersions = { {"JianHua", 19}, {"ZhiGuo", 19}, {"JianGuo", 18}, {"ZhenHua", 20}, {"WeiGuo", 19}, {"ZhangLei", 19}, {"LiHua", 20}, {"LiWei", 18}, }
    

分割

std::partition

  • 作用:分割容器,使满足谓词的元素在前,不满足的在后。
  • 示例

      vector<std::string> testArrgs = {"LiHua", "ZhangHong", "HeDa", "LiWei", "ZhangLei", "WeiGuo", "ZhenHua"};
    
      // partition
      vector<std::string> partArrgs(testArrgs);
      std::partition(partArrgs.begin(), partArrgs.end(), [](const std::string& str) { return (str.compare(0, 5, "Zhang") == 0); });
      DumpVector("partArrgs", partArrgs);
    
  • 结果
    D: partArrgs: "ZhangLei", "ZhangHong", "HeDa", "LiWei", "LiHua", "WeiGuo", "ZhenHua",
    

std::stable_partition

  • 作用:类似partition,但保持相同元素的相对顺序不变。
  • 示例

      vector<std::string> testArrgs = {"LiHua", "ZhangHong", "HeDa", "LiWei", "ZhangLei", "WeiGuo", "ZhenHua"};
    
      // stable_partition
      vector<std::string> stPartArrgs(testArrgs);
      std::stable_partition(stPartArrgs.begin(), stPartArrgs.end(), [](const std::string& str) { return (str.compare(0, 5, "Zhang") == 0); });
      DumpVector("stPartArrgs", stPartArrgs);
    
  • 结果
    D: stPartArrgs: "ZhangHong", "ZhangLei", "LiHua", "HeDa", "LiWei", "WeiGuo", "ZhenHua",
    

拷贝与生成

std::copy

  • 作用:拷贝容器或范围内的元素到另一位置。
  • 示例

      vector<std::string> srcArrgs = {"LiHua", "ZhangHong", "HeDa", "LiWei", "ZhangLei", "WeiGuo", "ZhenHua"};
    
      // copy
      vector<std::string> dstCopyArrgs;
      std::copy(srcArrgs.begin(), srcArrgs.end(), std::back_inserter(dstCopyArrgs));
      DumpVector("dstCopyArrgs", dstCopyArrgs);
    
  • 结果
    D: dstCopyArrgs: "LiHua", "ZhangHong", "HeDa", "LiWei", "ZhangLei", "WeiGuo", "ZhenHua",
    

std::copy_if

  • 作用:根据谓词条件拷贝元素。
  • 示例

      vector<std::string> srcArrgs = {"LiHua", "ZhangHong", "HeDa", "LiWei", "ZhangLei", "WeiGuo", "ZhenHua"};
    
      // copy_if
      vector<std::string> dstCopyIfArrgs;
      std::copy_if(srcArrgs.begin(), srcArrgs.end(), std::back_inserter(dstCopyIfArrgs), [](const std::string& str) { return (str.compare(0, 5, "Zhang") == 0); });
      DumpVector("dstCopyIfArrgs", dstCopyIfArrgs);
    
  • 结果
    D: dstCopyIfArrgs: "ZhangHong", "ZhangLei",
    

std::copy_n

  • 作用:拷贝指定数量的元素。
  • 示例

      vector<std::string> srcArrgs = {"LiHua", "ZhangHong", "HeDa", "LiWei", "ZhangLei", "WeiGuo", "ZhenHua"};
    
      // copy_n
      vector<std::string> dstCopyNArrgs;
      std::copy_n(srcArrgs.begin(), 3, std::back_inserter(dstCopyNArrgs));
      DumpVector("dstCopyNArrgs", dstCopyNArrgs);
    
  • 结果
    D: dstCopyNArrgs: "LiHua", "ZhangHong", "HeDa",
    

std::generate

  • 作用:使用生成器函数填充容器。
  • 示例
      // generate
      vector<std::string> genArrgs(5);
      std::generate(genArrgs.begin(), genArrgs.end(), [](){ return "Hello"; });
      DumpVector("genArrgs", genArrgs);
    
  • 结果
    D: genArrgs: "Hello", "Hello", "Hello", "Hello", "Hello",
    

std::generate_n

  • 作用:生成指定数量的元素填充容器。
  • 示例
      // generate_n
      vector<std::string> genNArrgs;
      std::generate_n(std::back_inserter(genNArrgs), 3, [](){ return "Hello"; });
      DumpVector("genNArrgs", genNArrgs);
    
  • 结果
    D: genNArrgs: "Hello", "Hello", "Hello",
    

集合操作

std::merge

  • 作用:生成指定数量的元素填充容器。
  • 示例

      vector<std::string> srcArrgs = {"Vince Carter", "Rose", "James"};
    
      // merge
      vector<std::string> mergeArrgs;
      vector<std::string> tmpArrgs = {"Irving"};
      std::merge(srcArrgs.begin(), srcArrgs.end(), tmpArrgs.begin(), tmpArrgs.end(), std::back_inserter(mergeArrgs));
      DumpVector("mergeArrgs", mergeArrgs);
    
  • 结果
    D: mergeArrgs: "Irving", "Vince Carter", "Rose", "James",
    

std::inplace_merge

  • 作用:就地归并两个有序范围。
  • 示例

      vector<std::string> srcArrgs = {"Vince Carter", "Rose", "James"};
    
      // inplace_merge
      vector<std::string> inplaceMergeArrgs(srcArrgs);
      std::inplace_merge(inplaceMergeArrgs.begin(), inplaceMergeArrgs.begin() + 2, inplaceMergeArrgs.end());
      DumpVector("inplaceMergeArrgs", inplaceMergeArrgs);
    
  • 结果

    D: inplaceMergeArrgs: "James", "Vince Carter", "Rose",
    
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以上只是一部分STL算法的简单概述,每一个算法都有其特定的使用场景和规则,具体使用时需要参考相关文档或者教程进行深入理解和学习。
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存储 安全 C++
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C++ 索引 容器
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15天前
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存储 算法 C语言
【C++】详解STL的适配器容器之一:优先级队列 priority_queue
【C++】详解STL的适配器容器之一:优先级队列 priority_queue
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设计模式 存储 缓存
【C++】详解STL容器之一的deque和适配器stack,queue
【C++】详解STL容器之一的deque和适配器stack,queue