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c++中ifstream一次读取文件

by wittx 2021-06-25

c++中一次读取整个文件的内容的方法：

读取至char*的情况

std::ifstream t;  
int length;  
t.open("file.txt");      // open input file  
t.seekg(0, std::ios::end);    // go to the end  
length = t.tellg();           // report location (this is the length)  
t.seekg(0, std::ios::beg);    // go back to the beginning  
buffer = new char[length];    // allocate memory for a buffer of appropriate dimension  
t.read(buffer, length);       // read the whole file into the buffer  
t.close();                    // close file handle  
  
// ... do stuff with buffer here ...

读取至std::string的情况：

第一种方法：

#include   
#include   
#include   
  
std::ifstream t("file.txt");  
std::string str((std::istreambuf_iterator<char>(t)),  
                 std::istreambuf_iterator<char>());

第二种方法：

#include   
#include   
#include   
std::ifstream t("file.txt");  
std::stringstream buffer;  
buffer << t.rdbuf();  
std::string contents(buffer.str());