sstream().map()不为空添加

要在sstream中使用map，您需要先将字符串分割成单词，并将其添加到map中。以下是一种实现的方法：

#include <string>
#include <sstream>
#include <map>
#include <iostream>
using namespace std;

int main() {
    string str = "AA BB CC B 1 123";
    istringstream stream(str);
    string word;
    map<string, int> wordCount;

    while (stream >> word) {
        wordCount[word]++;
    }

    // 检查map是否为空，如果为空则添加一个元素
    if (wordCount.empty()) {
        wordCount["default"] = 1;
    }

    for (const auto& pair : wordCount) {
        cout << pair.first << ": " << pair.second << endl;
    }

    return 0;
}

这段代码将字符串`str`分割为单词，并使用map `wordCount` 存储每个单词的出现次数。然后，我们检查map是否为空，如果为空，则添加一个名为"default"的元素。最后，我们遍历map并输出每个单词及其出现次数。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
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