如何保存文本文件而不在末尾键入“.txt”？

Question

我的计划（C++）：

#include <iostream> 
#include <fstream> 
#include <cstdlib> 
using namespace std; 

float x, y, z; 
char d[20]; 

int main() 
{ 
    cin.getline >>d; 
    x=111; 
    y=222; 
    z=333; 
    ofstream meuarquivo; 
    meuarquivo.open (d".txt"); 
    meuarquivo << x << "\n"; 
    meuarquivo << y << "\n"; 
    meuarquivo << z << "\n"; 

    meuarquivo.close(); 

    return 0; 
} 

我想写类似“ThatsMyProgram”，我想程序将此文件保存为“ThatsMyProgram.txt”。我怎样才能做到这一点？

Answer 1

使用std::string，这对于级联定义operator +：

#include <iostream> 
#include <fstream> 
#include <cstdlib> 
#include <string> 

int main() 
{ 
    std::string filename; 
    std::getline(std::cin, filename); 

    std::ofstream file((filename + ".txt").c_str()); 

    // use stream here. 
}