C语言 %d 是什么意思？为什么是 d 而不是另一个字母？
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What does %d mean? Why d and not another letter?
提问by Abdul Montaqim
I'm just starting out learning C and wanted to ask some very elementary questions. I don't have any programming background at all. I'm just at the very start of a tutorial (http://www.cprogramming.com/tutorial/c-tutorial.html) and there's some things it doesn't explain. Like, for example, in this following introductory simple program…
我刚开始学习 C，想问一些非常基本的问题。我根本没有任何编程背景。我刚开始学习教程（http://www.cprogramming.com/tutorial/c-tutorial.html），有些东西没有解释。例如，在下面的介绍性简单程序中……
Question: why does he use "%d" – why d and not another letter? I understand the % is the modulo operand, meaning remainder, but why d? I understand that stdio.h imports a library/glossary of terms to use, such as printf and so on… is %d the same as that? :
问题：为什么他使用“%d”——为什么是 d 而不是另一个字母？我知道 % 是模操作数，意思是余数，但为什么是 d？我知道 stdio.h 导入了要使用的术语库/词汇表，例如 printf 等…… %d 与此相同吗？：
#include <stdio.h>
int main()
{
int this_is_a_number;
printf( "Please enter a number: " );
scanf( "%d", &this_is_a_number );
printf( "You entered %d", this_is_a_number );
getchar();
return 0;
}
回答by David Schwartz
Actually %is not the modulo operand or modulo operator here because it's included inside a string. It's just a character chosen to separate literal text from parameters. And dis used because it performs input and output in decimal (base 10).
实际上%这里不是模操作数或模运算符，因为它包含在字符串中。它只是一个选择来将文字文本与参数分开的字符。和d被使用，因为它在执行输入和输出decimal（基体10）。
回答by Vincent L.
In this case is not a modulo operator but a sign meaning you want to display the sub-sequent information in a certain format. The letter is called a specifier.
在这种情况下不是模运算符而是一个符号，表示您希望以某种格式显示后续信息。该字母称为说明符。
%dmeans you're going to display it as a decimal integer. %fwould display it as a float number etc.
%d意味着您要将其显示为十进制整数。%f将其显示为浮点数等。
More in the man: http://linux.die.net/man/3/printf
