C++ 如何将整个字符数组设置为空格？
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C++ How do I set an entire character array to blank spaces?
提问by tomkelley13
Say I have the following declared variable:
假设我有以下声明的变量：
char mychararray[35];
and I want to set every character in the array to a blank space... How can I do that?
我想将数组中的每个字符设置为一个空格......我该怎么做？
My instructor told me all I had to do was put
我的导师告诉我我所要做的就是把
mychararray = "";
but that didn't work at all...
但这根本不起作用......
Am I using an outdated version of Visual Studio (2012), or is this just a bad initialization? If it is the latter, please explain how to make all the characters a blank space.
我使用的是过时版本的 Visual Studio (2012)，还是这只是一个错误的初始化？如果是后者，请说明如何使所有字符都为空格。
Thanks in advance!
提前致谢！
回答by Ishamael
You can initialize it the way your instructor suggested as you declare the array:
您可以在声明数组时按照教师建议的方式对其进行初始化：
char mychararray[35] = "";
It will set the array to an empty string.
它会将数组设置为空字符串。
If you want to make it an empty string later, then you can just do
如果你想稍后使它成为一个空字符串，那么你可以这样做
mychararray[0] = 'memset(mychararray, ' ', 34);
mychararray[34] = 'char mychararray[35] = "";
';
';
If you want to make it an array consisting of 34 spaces (35th character being null terminator), then
如果要使其成为由 34 个空格（第 35 个字符为空终止符）组成的数组，则
#include <algorithm>
#include <iterator>
int main()
{
char c[35] = "Hello, world!";
std::fill(std::begin(c), std::end(c), 'std::string blanks(35, ' ');
');
// c will contain only zeros now.
}
回答by Andy Prowl
That is not initialization, it's assignment. For initializing an array when declaring it, you can write:
那不是初始化，而是赋值。要在声明数组时初始化数组，您可以编写：
memset(mychararray, ' ', 34);
mychararray[34]='char mychararray[35] = {};
';
If you already have an array and want to set it to zero, you can use std::fill:
如果您已经有一个数组并希望将其设置为零，则可以使用std::fill：
However, C-style arrays are not very popular in modern C++. Prefer using std::string(which you can clear using the clear()member function), or std::array<char, N>if you need the size to be known at compile-time.
然而，C 风格的数组在现代 C++ 中并不是很流行。更喜欢使用std::string（您可以使用clear()成员函数清除它），或者std::array<char, N>如果您需要在编译时知道大小。
回答by xtofl
Although you could use std::fill_n(array, 35, ' '), you're probably better of using an std::string, the preferred string class in C++. Don't have to care about zero-termination or anything.
尽管您可以使用std::fill_n(array, 35, ' ')，但最好使用std::stringC++ 中首选的字符串类 。不必关心零终止或任何事情。
回答by Pradhan
std::memsetis your friend.
std::memset是你的朋友。
If you want to initialize the array with all elements being '\0', you have a neater way through aggregate initialization:
如果要使用所有元素初始化数组'\0'，则可以通过聚合初始化更简洁的方法：
回答by Marcus Müller
C++ doesn't initialie charto ' '(which has the ascii value 0x20, btw); in fact, array initialization without specifying what to use for initialization doesn't necessarily take place (arrays in local scope are left uninitialized).
C++ 不会初始化char为' '（ascii 值为 0x20，顺便说一句）；事实上，没有指定用于初始化的数组初始化并不一定会发生（局部范围内的数组未初始化）。
