使用来自文件的输入运行 C++ 的命令
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Command to run C++ with input from file
提问by Partharaj Deb
myC.cpp
cpp文件
#include<stdio.h>
#include<iostream>
using namespace std;
int main()
{
freopen("input.txt","r",stdin); // All inputs from 'input.txt' file
int n,m;
cin>>n>>m;
cout<<(n+m)<<endl;
return 0;
}
The file input.txtmay contains:
该文件input.txt可能包含：
Input.txt
输入.txt
10 20
10 20
Command lines to build and run the code-
用于构建和运行代码的命令行 -
g++ myC.cpp -o myC
myC
It produces output 30getting input from input.txtfile.
它产生30从input.txt文件中获取输入的输出。
Now I am looking for a command which will similarly get input from a file, but want to avoid using freopen() inside the code.
现在我正在寻找一个命令，它同样可以从文件中获取输入，但希望避免在代码中使用 freopen()。
It might be something like this-
可能是这样的——
g++ myC.cpp -o myC // To compile
myC -i input.txt // To run with input
回答by Jacob Pollack
You need to pipe the input file to your program when invoking it from the command line. Consider the following program:
从命令行调用输入文件时，您需要将输入文件通过管道传输到您的程序。考虑以下程序：
#include <stdio.h>
int main( void ) {
int a, b;
scanf( "%d", &a );
scanf( "%d", &b );
printf( "%d + %d = %d", a, b, ( a + b ) );
return 0;
}
... say I compiled it as "test.exe", I would invoke it as follows to pipe the input text file.
...说我将它编译为“test.exe”，我会按如下方式调用它来管道输入文本文件。
./test.exe < input.txt
回答by David Rodríguez - dribeas
While there is no single command that will do that (the compiler will not execute your code), for small tests I tend to run a single command line that will compile and execute if the build was correct:
虽然没有单个命令可以做到这一点（编译器不会执行您的代码），但对于小型测试，我倾向于运行一个命令行，如果构建正确，它将编译和执行：
g++ -o myC myC.cpp && ./myC input.txt
g++ -o myC myC.cpp && ./myC input.txt
Of course that requires changing your program so that the filename is taken as an argument, but that should be simple enough.
当然，这需要更改您的程序，以便将文件名作为参数，但这应该足够简单。
