scanf() printf() 后无回车

Question

我有以下代码从用户输入中读取 4 个数字：

#include <stdio.h>
#include <stdlib.h>

#define MAX_NUMS 4

int main()
{
    int nums[MAX_NUMS];

    int i;
    int num;

    for (i = 0; i < MAX_NUMS; i++)
    {
        do
        {
            printf("Enter a value between 1 and 9: ");
            scanf("%i",&num);
        }
        while(num > 9 || num < 1);

        nums[i] = num;
    }

    return 0;
}

当我运行它时，我得到以下输出：

user@USER:/cygdrive/d
$ ./test.exe
Enter a value between 1 and 9: 1
                                Enter a value between 1 and 9: 2
                                                                Enter a value between 1 and 9: 3
                                                                                                Enter a value between 1 and 9: 4
                                                                                                                                user@USER:/cygdrive/d
$

为什么输入数字后按回车没有回车？我错过了什么吗？

我在cygwin上：

user@USER:/cygdrive/d
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-cygwin/9.3.0/lto-wrapper.exe
Target: x86_64-pc-cygwin
Configured with: /cygdrive/i/szsz/tmpp/gcc/gcc-9.3.0-2.x86_64/src/gcc-9.3.0/configure --srcdir=/cygdrive/i/szsz/tmpp/gcc/gcc-9.3.0-2.x86_64/src/gcc-9.3.0 --prefix=/usr --exec-prefix=/usr --localstatedir=/var --sysconfdir=/etc --docdir=/usr/share/doc/gcc --htmldir=/usr/share/doc/gcc/html -C --build=x86_64-pc-cygwin --host=x86_64-pc-cygwin --target=x86_64-pc-cygwin --without-libiconv-prefix --without-libintl-prefix --libexecdir=/usr/lib --enable-shared --enable-shared-libgcc --enable-static --enable-version-specific-runtime-libs --enable-bootstrap --enable-__cxa_atexit --with-dwarf2 --with-tune=generic --enable-languages=c,c++,fortran,lto,objc,obj-c++ --enable-graphite --enable-threads=posix --enable-libatomic --enable-libgomp --enable-libquadmath --enable-libquadmath-support --disable-libssp --enable-libada --disable-symvers --with-gnu-ld --with-gnu-as --with-cloog-include=/usr/include/cloog-isl --without-libiconv-prefix --without-libintl-prefix --with-system-zlib --enable-linker-build-id --with-default-libstdcxx-abi=gcc4-compatible --enable-libstdcxx-filesystem-ts
Thread model: posix
gcc version 9.3.0 (GCC)
user@USER:/cygdrive/d
$ uname -a
CYGWIN_NT-10.0 STEPAN 3.1.5(0.340/5/3) 2020-06-01 08:59 x86_64 Cygwin
user@USER:/cygdrive/d
$ echo $TERM
xterm-256color

Answer 1

似乎在您的特定环境中，您按下确认输入的 Enter 键被解释为原始'\n'。这个字符的原意，其实就是line feed，意思是“换行而不执行回车”（'\r'）。

在大多数终端中，回车键将\r 和\n 的效果相加，而您的情况不会发生这种情况。

要解决此问题，请尝试在输入插入后手动插入 '\r'：

do
{
    printf("Enter a value between 1 and 9: ");
    scanf("%i",&num);
    printf("\r");
}
while(num > 9 || num < 1);