检查以确保argv [1]是一个整数c ++ [英] Checking to make sure argv[1] is an integer c++

问题描述

对于我的程序，我必须确保用户只输入一个正整数。例如如果用户输入12hi它不应该运行程序和打印到std错误。我不太确定如何实现这个。

For my program I have to make sure the user only inputs a positive INTEGER. for example if the user inputted 12hi it should not run the program and print to std error. I am not quite sure how to implement this.

int main(int argc, char *argv[])   
{ 
    if(atoi(argv[1]) < 1)
    {
        cerr << "ERROR!"<< endl;
        return 1;
    }
    return 0;
}

推荐答案

href =http://en.cppreference.com/w/cpp/io/basic_istringstream =nofollow> std :: istringstream 并确保所有数据均已处理：

Pass it to a std::istringstream and ensure all data was processed:

if (a_argc > 1)
{
    std::istringstream in(a_argv[1]);
    int i;
    if (in >> i && in.eof())
    {
        std::cout << "Valid integer\n";
    }
}

查看在线演示 http://ideone.com/8bEYJq 。

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