C语言 将字符串添加到 C 中的字符数组
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Add string to char array in C
提问by skylerl
I have a C array called buf. Here is it's definition:
我有一个名为 buf 的 C 数组。这是它的定义：
char buf[1024];
char buf[1024];
Now, my current code takes from stdinand uses fgets()to set that array, however I wish to use code to set it instead. Right now the line that sets buf looks like this:
现在，我当前的代码从stdin并用于fgets()设置该数组，但是我希望使用代码来设置它。现在设置 buf 的行如下所示：
fgets(buf, 1024, stdin);
fgets(buf, 1024, stdin);
Basically, I want to replace stdin, with say... "My String". What's the best way to do this?
基本上，我想用说...“我的字符串”来替换标准输入。做到这一点的最佳方法是什么？
回答by Cedric H.
Look for sprintf, for example here: Cpp reference
寻找sprintf，例如在这里：Cpp 参考
Edit:
编辑：
sprintf(buf, "My string with args %d", (long) my_double_variable);
Edit 2:
编辑2：
As suggested to avoid overflow (but this one is standard C) you can use snprintf.
根据建议避免溢出（但这是标准 C），您可以使用snprintf。
回答by user411313
snprintf is only C99 not C89, sprintf_s/strcpy_s are only MSVC, not C89, not C99.
snprintf 只是 C99 不是 C89，sprintf_s/strcpy_s 只是 MSVC，不是 C89，不是 C99。
char *mystr="come from stdin or file or ...";
char buf[1024];
...
memset(buf,0,sizeof buf);
strncpy(buf,mystr,(sizeof buf)-1);
or non array:
或非数组：
#define BUFLEN 512
char *mystr="come from stdin or file or ...";
char *buf;
...
char *buf=calloc(1,BUFLEN);
strncpy(buf,mystr,BUFLEN-1);
It works on all ANSI C environments.
它适用于所有 ANSI C 环境。
回答by James Curran
strcpy(buf, "My String");
Microsoft's compiler also include a function strcpy_s, which is a "safe" version of strcpy. It makes sure that you won't overrun buf. In this particular case, that's probably not a problem, but you shoul dknow about. But, be aware, it's not available with any other compiler, so it can;t be used where portable is needed.
Microsoft 的编译器还包含一个函数 strcpy_s，它是 strcpy 的“安全”版本。它确保您不会超支buf。在这种特殊情况下，这可能不是问题，但您应该知道。但是，请注意，它不适用于任何其他编译器，因此不能用于需要可移植性的地方。
strcpy_s(buf, sizeof(buf), "My String");
回答by rubber boots
There are many variants, some have been already proposed, some not:
有很多变体，有些已经被提出，有些还没有：
...
char input[] = "My String";
strcpy(buf, input);
strncpy(buf, input, sizeof(buf));
sscanf(input, "%s", buf);
sprintf(buf, "%s", input);
memcpy(buf, input, strlen(input));
...
most of them are unsure/insecure. What exactly should be taken depends on what you really want todo in your code.
他们中的大多数人不确定/不安全。究竟应该采取什么取决于您真正想在代码中做什么。
Regards
问候
rbo
红包
回答by atlpeg
Verbose but safe:
冗长但安全：
int copy_size = sizeof( buf ) - 1 < strlen( MyString ) ? sizeof( buf ) - 1 : strlen( MyString );
memset( buf, 0, copy_size + 1 );
memcpy( buf, MyString, copy_size );
