假设我有
string sentence{"Hello how are you."}
我希望将字符串中的“Hello”替换为“你好”，得到的字符串仍然包含“how are you”。应该如何实现？
我尝试了以下代码：
stringstream ss(sentence);
ss>> string junkWord;//to get rid of first word
但是当我这样做时：
cout<<sentence;//still prints out "Hello how are you"
stringstream 不会改变实际的字符串。我也尝试使用 strtok 但它与 string 不兼容。#include <iostream>
#include <string>
int main()
{
std::string sentence{"Hello how are you."};
std::string::size_type n = 0;
n = sentence.find_first_not_of( " \t", n );
n = sentence.find_first_of( " \t", n );
sentence.erase( 0, sentence.find_first_not_of( " \t", n ) );
std::cout << '\"' << sentence << "\"\n";
return 0;
}
"how are you."
str=str.substr(str.find_first_of(" \t")+1);
测试完成：
string sentence="Hello how are you.";
cout<<"Before:"<<sentence<<endl;
sentence=sentence.substr(sentence.find_first_of(" \t")+1);
cout<<"After:"<<sentence<<endl;
执行：
> ./a.out
Before:Hello how are you.
After:how are you.
find_first_of("<list of characters>").
在我们的情况下，字符列表包括空格和制表符。这将搜索任何列表中的第一个出现并返回一个迭代器。之后，添加 +1 会将位置移动一个字符。然后，位置指向行的第二个单词。Substr(pos) 将提取从位置开始直到字符串的最后一个字符的子字符串。
string sentence{"Hello how are you."};
stringstream ss{sentence};
string junkWord;
ss >> junkWord;
cout<<sentence.substr(junkWord.length()+1); //string::substr
然而，这也取决于您想进一步做什么。
有无数种方法可以做到这一点。我认为我会选择这个：
#include <iostream>
#include <string>
int main() {
std::string sentence{"Hello how are you."};
// First, find the index for the first space:
auto first_space = sentence.find(' ');
// The part of the string we want to keep
// starts at the index after the space:
auto second_word = first_space + 1;
// If you want to write it out directly, write the part of the string
// that starts at the second word and lasts until the end of the string:
std::cout.write(
sentence.data() + second_word, sentence.length() - second_word);
std::cout << std::endl;
// Or, if you want a string object, make a copy from the start of the
// second word. substr copies until the end of the string when you give
// it only one argument, like here:
std::string rest{sentence.substr(second_word)};
std::cout << rest << std::endl;
}
first_space != std::string::npos，这意味着空格未被找到。为了清晰起见，我的示例代码中省略了这个检查 :)string::find() 来查找第一个空格。一旦你得到了它的索引，就可以使用 string::substr() 从空格之后的索引开始获取子字符串，一直到字符串的末尾。std::string subStr = sentence.substr(sentence.find_first_not_of(" \t\r\n", sentence.find_first_of(" \t\r\n", sentence.find_first_not_of(" \t\r\n"))));
工作示例：
#include <iostream>
#include <string>
void main()
{
std::string sentence{ "Hello how are you." };
char whiteSpaces[] = " \t\r\n";
std::string subStr = sentence.substr(sentence.find_first_not_of(whiteSpaces, sentence.find_first_of(whiteSpaces, sentence.find_first_not_of(whiteSpaces))));
std::cout << subStr;
std::cin.ignore();
}
这里是如何使用 stringstream 来提取垃圾词，同时忽略前后的任何空格（使用 std::ws），然后获取剩余的句子，并具备健壮的错误处理...
std::string sentence{"Hello how are you."};
std::stringstream ss{sentence};
std::string junkWord;
if (ss >> junkWord >> std::ws && std::getline(ss, sentence, '\0'))
std::cout << sentence << '\n';
else
std::cerr << "the sentence didn't contain ANY words at all\n";
点击此处在ideone上查看运行结果...
#include <iostream> // cout
#include <string> // string
#include <sstream> // string stream
using namespace std;
int main()
{
string testString = "Hello how are you.";
istringstream iss(testString); // note istringstream NOT sstringstream
char c; // this will read the delima (space in this case)
string firstWord;
iss>>firstWord>>c; // read the first word and end after the first ' '
cout << "The first word in \"" << testString << "\" is \"" << firstWord << "\""<<endl;
cout << "The rest of the words is \"" <<testString.substr(firstWord.length()+1) << "\""<<endl;
return 0;
}
输出
"Hello how are you."中的第一个单词是"Hello" 其余的单词是"how are you."
std::getline：http://ideone.com/IxZRAt 。不过在任何情况下我都不会使用这种方法... - MatthiasB