如何在 C 中读入 Enter 键作为输入？

Question

如何在 C 语言中读取 Enter 键作为输入？我想要这样的程序：

"Please enter a key to go to next line"

如何在 C 中添加这种类型的选项？

我是编程新手。

Answer 1

您可以使用 stdio.h 中的 getc 函数等待按键被按下。此 C 代码将等待按下回车键，然后输出“继续！”：

#include <stdio.h>

int main(){
    printf("Press any key to continue");
    getc(stdin);
    printf("Continued!");
    return 0;
}

Answer 2

如果我理解你的问题，你可以写：

printf("Press ENTER key to Continue\n");  
getchar();

或者

printf("Press Any Key to Continue\n");
getch();

Answer 3

C:

中的一堆 getc() 演示

1。要同时打印出输入的密钥，请执行以下操作：

read_in_any_key.c:

#include <stdio.h>

int main()
{
    printf("Press any key followed by Enter, or just Enter alone, to continue: ");
    int c = getc(stdin);
    printf("The first character you entered is decimal %i (\"%c\").\n", c, c);

    return 0;
}

示例运行和输出。请注意，在上一个示例中，我单独按了 Enter，因此它会将其打印为换行符。每个键的十进制数可以在 ASCII table 中找到，例如：https://en.wikipedia.org/wiki/ASCII#Control_code_chart.

eRCaGuy_hello_world/c$ gcc -Wall -Wextra -Werror -O3 -std=c17 read_in_enter_key.c -o bin/a && bin/a
Press any key followed by Enter, or just Enter alone, to continue: abc
The first character you entered is decimal 97 ("a").

eRCaGuy_hello_world/c$ gcc -Wall -Wextra -Werror -O3 -std=c17 read_in_enter_key.c -o bin/a && bin/a
Press any key followed by Enter, or just Enter alone, to continue: def
The first character you entered is decimal 100 ("d").

eRCaGuy_hello_world/c$ gcc -Wall -Wextra -Werror -O3 -std=c17 read_in_enter_key.c -o bin/a && bin/a
Press any key followed by Enter, or just Enter alone, to continue: FTL
The first character you entered is decimal 70 ("F").

eRCaGuy_hello_world/c$ gcc -Wall -Wextra -Werror -O3 -std=c17 read_in_enter_key.c -o bin/a && bin/a
Press any key followed by Enter, or just Enter alone, to continue: 
The first character you entered is decimal 10 ("
").

2。要打印出所有键入的键，以防在按 Enter 之前按下多个键，请执行以下操作：

read_in_any_key.c:

#include <stdint.h>  // For `uint8_t`, `int8_t`, etc.
#include <stdio.h>   // For `printf()`

// int main(int argc, char *argv[])  // alternative prototype
int main()
{
    printf("Press any key followed by Enter, or just Enter alone, to continue: ");
    int c = getc(stdin);
    printf("The first character you entered is decimal %i (\"%c\").\n", c, c);

    // If you entered one or more characters above before pressing Enter, they
    // are still in the stdin input stream's buffer, so let's read those out
    // too, up to the newline char (`'\n'`) created by pressing Enter.
    uint32_t charNum = 2;
    while (c != '\n')
    {
        c = getc(stdin);
        if (c == EOF)
        {
            printf("Failed to get char!\n");
            break;
        }
        printf("char %-2u = decimal %i (\"%c\").\n", charNum, c, c);
        charNum++;
    }

    return 0;
}

示例运行并输出。我输入 abcdefghijklmnop 然后按 Enter:

eRCaGuy_hello_world/c$ gcc -Wall -Wextra -Werror -O3 -std=c17 read_in_any_key.c -o bin/a && bin/a
Press any key followed by Enter, or just Enter alone, to continue: abcdefghijklmnop
The first character you entered is decimal 97 ("a").
char 2  = decimal 98 ("b").
char 3  = decimal 99 ("c").
char 4  = decimal 100 ("d").
char 5  = decimal 101 ("e").
char 6  = decimal 102 ("f").
char 7  = decimal 103 ("g").
char 8  = decimal 104 ("h").
char 9  = decimal 105 ("i").
char 10 = decimal 106 ("j").
char 11 = decimal 107 ("k").
char 12 = decimal 108 ("l").
char 13 = decimal 109 ("m").
char 14 = decimal 110 ("n").
char 15 = decimal 111 ("o").
char 16 = decimal 112 ("p").
char 17 = decimal 10 ("
").

3。要仅在单独按下 `Enter` 时继续，之前没有其他任何东西，请执行以下操作：

read_until_only_enter_key.c:

#include <stdbool.h> // For `true` (`1`) and `false` (`0`) macros in C
#include <stdio.h>   // For `printf()`

// Clear the stdin input stream by reading and discarding all incoming chars up to and including
// the Enter key's newline ('\n') char. Once we hit the newline char, stop calling `getc()`, as
// calls to `getc()` beyond that will block again, waiting for more user input.
void clearStdin()
{
    // keep reading 1 more char as long as the end of the stream, indicated by the newline char,
    // has NOT been reached
    while (true)
    {
        int c = getc(stdin);
        if (c == EOF || c == '\n')
        {
            break;
        }
    }
}

// Returns true if only Enter was pressed, and false otherwise
bool getOnlyEnterKeypress()
{
    bool onlyEnterPressed = false;
    printf("Press ONLY the Enter key to continue: ");
    int firstChar = getc(stdin);
    if (firstChar == '\n')
    {
        printf("Good! You pressed ONLY the Enter key!\n");
        onlyEnterPressed = true;
    }
    else
    {
        printf("You failed. You pressed another key first.\n");
        clearStdin();
    }
    return onlyEnterPressed;
}

// int main(int argc, char *argv[])  // alternative prototype
int main()
{
    while (!getOnlyEnterKeypress()) {};

    return 0;
}

示例运行并输出。请注意，当我只按下 Enter 时，程序直到最后才退出，之前没有更多的键。

eRCaGuy_hello_world/c$ gcc -Wall -Wextra -Werror -O3 -std=c17 read_until_only_enter_key.c -o bin/a && bin/a
Press ONLY the Enter key to continue: a
You failed. You pressed another key first.
Press ONLY the Enter key to continue: abc
You failed. You pressed another key first.
Press ONLY the Enter key to continue: w
You failed. You pressed another key first.
Press ONLY the Enter key to continue:
Good! You pressed ONLY the Enter key!

如果您想立即阅读按键，而不是等待按下 Enter 键，请参阅“Going”顶部的 link更多”部分就在下面。

参考文献：

Related/Going 更进一步：

[我的回答]如何立即读取按键而不是等待输入：Capture characters from standard input without waiting for enter to be pressed
What is the equivalent to getch() & getche() in Linux?
How to avoid pressing Enter with getchar() for reading a single character only?
Read Key pressings in C ex. Enter key

Answer 4

只有一个其他答案正确地涉及到这一点。不要假设您的用户会服从您，即使他或她有意服从。

// Ask user to do something
printf( "Press Enter to continue: " );
fflush( stdout );

// Wait for user to do it
int c;
do c = getchar();
while ((c != EOF) and (c != '\n'));

这将丢弃其他输入，直到按下 Enter 键或到达 EOF，使您的输入流处于已知状态。

如果你希望有无缓冲的输入，那就完全不同了。

如何在 C 中读入 Enter 键作为输入？

How do I read in the Enter key as an input in C?

c

stdin

input

1。要同时打印出输入的密钥，请执行以下操作：

2。要打印出所有键入的键，以防在按 Enter 之前按下多个键，请执行以下操作：

3。要仅在单独按下 Enter 时继续，之前没有其他任何东西，请执行以下操作：

参考文献：

Related/Going 更进一步：

3。要仅在单独按下 `Enter` 时继续，之前没有其他任何东西，请执行以下操作：