stringstream

stringstream

2019.02.25 11:15:03字数 71阅读 299

A stringstream associates a string object with a stream allowing you to read from the string as if it were a stream (like cin).

 

注意：  小心stringstream.str()字符串用法的陷阱

streamstring在调用str()时，会返回临时的string对象。而因为是临时的对象，所以它在整个表达式结束后将会被析构。由于紧接着调用的c_str()函数将得到的是这些临时string对象对应的C string，而它们在这个表达式结束后是不被引用的，进而这块内存将被回收而可能被别的内容所覆盖

接口函数

clear() — to clear the stream
str() — to get and set string object whose content is present in stream.
operator << — add a string to the stringstream object.
operator >> — read something from the stringstream object,

应用

• 统计字符串中的单词数目
• 统计字符串中的词频
• 去除字符串中的空格
• 字符串转换为数字
  示例来源

// A program to demonstrate the use of stringstream 
#include <iostream> 
#include <sstream> 
using namespace std; 
  
int main() 
{ 
    string s = "12345"; 
  
    // object from the class stringstream 
    stringstream geek(s); 
  
    // The object has the value 12345 and stream 
    // it to the integer x 
    int x = 0; 
    geek >> x; 
  
    // Now the variable x holds the value 12345 
    cout << "Value of x : " << x; 
  
    return 0; 
}