C++ cin 和 cout輸入輸出的一些常見用例介紹
1、標準輸入輸出
2、指定格式輸出-std::hex, std::oct,std::dex
int main()
{
//while (true)
{
int n;
std::cout << "please input n" << std::endl;
std::cin >> n;
std::cout << std::hex << n << std::endl;//16進制輸出
std::cout << std::oct << n << std::endl;//8進制輸出
std::cout << std::dec << n << std::endl;//10進制輸出
std::cout << std::fixed << n << std::endl;//10進制輸出
std::cout << "please input string" << std::endl;
std::string str;
std::cin >> str;
std::cout << str << std::endl;
}
return 1;
}
3、std::fixed, std:: scientific, std::cout.precision--四捨五入
int main()
{
double a = 3.1415926534;
double b = 2006.0;
double c = 1.0e-10;
std::cout.precision(5);//保留n位有效數字,其中最後一位是四捨五入之後的結果;默認情況下n=6
std::cout << "default:\n";
std::cout << a << '\n' << b << '\n' << c << '\n';
std::cout << '\n';
std::cout << "fixed:\n" << std::fixed;//控制小數點後面的打印數字個數的
std::cout << a << '\n' << b << '\n' << c << '\n';
std::cout << '\n';
std::cout << "scientific:\n" << std::scientific;
std::cout << a << '\n' << b << '\n' << c << '\n';
double s = 20.7843000;
std::cout << "s =" << s << std::endl;
int r = std::cout.precision(2);//return The previous value of precision() ,so r = 5
std::cout << "r =" << r << std::endl;
std::cout << s << std::endl;//會輸出21。
return 0;
}
4、cin 輸入,使用空白符來判定結束
5、 cin.getline 讀取一行
int main()
{
std::cout << "please input string" << std::endl;
char arrRead[100];
std::cin.getline(arrRead, 100);//cin.getline使用還行符判定結束
std::cout << arrRead << std::endl;
return 0;
}
6、cin.get
int main()
{
std::cout << "please input string" << std::endl;
char arrRead1[100];
char arrRead2[100];
std::cin.get(arrRead1, 100);//get 不再讀去並丟棄換行符,而是將其保存在輸入隊列中
std::cout << arrRead1 << std::endl;
std::cin.get(arrRead2, 100);//第二次的cin讀取上次的換行符,認爲到達行尾
std::cout << arrRead2 << std::endl;
return 0;
}
讀取下一行時添加get()