c++ - C++中的字符串连接问题

Question

我想连接一个包含路径和文件名的文件名。然后我可以打开并写入它。但我没有这样做。

char * pPath;
pPath = getenv ("MyAPP");
if (pPath!=NULL)
//printf ("The current path is: %s",pPath); // pPath = D:/temp

string str = "test.txt";
char *buf = new char[strlen(str)];
strcpy(buf,str);

fullName = ??  // how can I get D:/temp/test.txt 

ofstream outfile;
outfile.open(fullName);
outfile << "hello world" << std::endl;

outfile.close();

Answer 1

string str = "test.txt";
char *buf = new char[strlen(str)];
strcpy(buf,str);

应该是

string str = "test.txt";
char *buf = new char[str.size() + 1];
strcpy(buf,str.c_str());

但毕竟，你甚至不需要那个。 std::string 支持通过 operator+= 连接和从 char* 构造并公开一个 c_str 函数返回一个 C 风格的字符串:

string str(pPath); // construction from char*
str += "test.txt"; // concatenation with +=

ofstream outfile;
outfile.open(str.c_str());