C连接字符串变量字符串

Question

我尝试以以下形式连接 "string"，变量，"string"；

#include <stdio.h>

int main() {
        char *name = "Lannister";

        char write_letter[50] = "Here you are Mrs. ", name, " Welcome!\r\n"
                             "Getting Started\r\n"
                             "Interviews\r\n"
                             "Take-home Projects\r\n";
}

有人知道怎么做吗？

我看到了一个例子 sprintf(write_letter, "Here you are Mrs. %s Welcome!", 姓名); 但是当我使用大文本时非常困难。

Answer 1

您只能将 "..." "..." 表示法用于 编译时可计算常量表达式 。由于 name.

，您的是运行时构造

您需要使用 strcat、snprintf 等。

Answer 2

预处理器能够为您进行字符串连接，前提是涉及的所有字符串都是直接在彼此之后写入的，并且它们是纯常量字符串文字。即" "包围的东西，不是变量。例如 "hello" "world" 将被预处理器更改为 "helloworld"。

这不适用于变量。如果您有字符数组，则需要将它们与运行时间函数连接起来，例如 strcat.

Answer 3

作为 sprintf 的替代方法（使用 snprintf(NULL, 0, ...) 知道要为结果分配多少内存），您可以使用 strcat。但同样，您有责任分配足够的内存来包含最终字符串 !

Answer 4

如果名称已经在编译时确定，并且如果没有必要在运行时更改名称，那么一定要选择最简单的替代方案，即 -

#define NAME "Lannister"

char write_letter[] = "Here you are Mrs. " NAME " Welcome!\r\n"
                      "Getting Started\r\n"
                      "Interviews\r\n"
                      "Take-home Projects\r\n";

Compile with highest warning level set. When you do that you will get a warning similar to "initializer-string for array of chars is too long" (this is the warning generated by GCC). 50 is too small for this array hence I have allowed the compiler to decide the array size (i.e. 'write_letter[]').

如果您需要在运行时更改字符串，请使用 strcat() -

char write_letter[150] = "Here you are Mrs. ";
char *name = "Lannister";
char *write_letter_post = " Welcome!\r\n"
                          "Getting Started\r\n"
                          "Interviews\r\n"
                          "Take-home Projects\r\n";

strcat(write_letter, name);
strcat(write_letter, write_letter_post);
/*Use strncat() to prevent buffer overflow possibilities.*/

或者，sprintf() -

char *_write_letter = "Here you are Mrs. %s Welcome!\r\n"
                      "Getting Started\r\n"
                      "Interviews\r\n"
                      "Take-home Projects\r\n";
char *name = "Lannister";
char write_letter[150];

sprintf(write_letter, _write_letter, name);
/*Use snprintf() to prevent buffer overflow possibilities.*/

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