我正在研究将I2C消息系统的值连接在一起的字符串形式的C ++代码。我已经正确解决了消息传递问题，但是当我将字符串连接在一起时，代码错误地将多个字符串连接起来，而不仅仅是我想要的三个值。我写的代码如下：
void concatint(int value1, char address1, char address2)
{
int alive1 = static_cast<int>(address1);
int alive2 = static_cast<int>(address2);
char* alive3 = (char*)malloc(sizeof(address1));
char* alive4 = (char*)malloc(sizeof(address2));
//alive3 = address1;
//alive4 = address2;
sprintf(alive3, "%2d", address1);
sprintf(alive4, "%2d", address2);
if (value1 < 10)
readlength = 1;
if (value1 >= 10 && value1 < 100)
readlength = 2;
if (value1 >= 100 && value1 < 1000)
readlength = 3;
if (value1 >= 1000 && value1 < 10000)
readlength = 4;
if (value1 >= 10000 && value1 < 100000)
readlength = 5;
if (value1 >= 100000 && value1 < 1000000)
readlength = 6;
if (value1 >= 1000000 && value1 < 10000000)
readlength = 7;
if (value1 >= 10000000 && value1 < 100000000)
readlength = 8;
*writedata = 0;
itoa(value1, writedata, 10);
strcpy(writeaddress, &address1);
strcat(writeaddress, &address2);
strcat(writeaddress, writedata);
strcpy(readaddress, address1);
strcat(readaddress, address2);
typevalue = 1;
}
该函数的输入为：
concatint(5, ' ', ' ');
其中两个地址值是两个ASCii字符。
该代码的结果应为：''''5，并将ASCii字符连接到该值之前。但是，当我运行代码时，得到的结果是：
" \005 \0055"
我的代码似乎在我的字符之间连接了一个额外的字符，我不确定上面的代码在何处添加了该字符。我已经遍历了代码，一切都应该正常工作，不确定我的问题在哪里。
最佳答案
前八行的行为不确定：
void concatint(int value1, char address1, char address2)
{
int alive1 = static_cast<int>(address1);
int alive2 = static_cast<int>(address2);
// Note that address1 is a char, not a char*, and as such sizeof(address1)
// is guaranteed to be 1. Thus we allocate one byte of storage.
char * alive3 = (char*) malloc(sizeof(address1));
char * alive4 = (char*) malloc(sizeof(address2));
// Here we write two digits and a terminating NUL to that one byte
// => undefined behaviour. Cannot reason further about the program.
sprintf(alive3, "%2d", address1);
sprintf(alive4, "%2d", address2);
此外：
strcpy(writeaddress, &address1);
也不会工作。
address1是一个字符。 &address1是指向此字符的指针，但是后面没有尾随的NUL字符，因此它也不是传递给strcpy的有效指针。使用
std::string