BewareMyPower commented on PR #294:
URL:
https://github.com/apache/pulsar-client-cpp/pull/294#issuecomment-1619783898
In addition, I don't think use a null-terminated string as the tableview
value is good for C API. The value is actually a byte array rather than a
null-terminated string. Unlike the `TableView` class, it's okay to return a
`std::string`, which is actually a byte array in C++. For example, if the
producer sends 4 bytes: `[0x01, 0x00, 0x02, 0x00]`, you can never know the
length.
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static void get_value(char **value) {
char *data = (char *)malloc(4);
data[0] = 0x01;
data[1] = 0x00;
data[2] = 0x02;
data[3] = 0x00;
*value = data;
}
int main(int argc, char *argv[]) {
char *value;
get_value(&value);
printf("length: %zu\n", strlen(value));
return 0;
}
```
The code example is a demo to show the difference between a byte array and a
null-terminated string.
So it's better to add a length parameter like:
```c
#include <stdio.h>
#include <stdlib.h>
static void get_value(char **value_ptr, size_t *value_len) {
char *data = (char *)malloc(4);
data[0] = 0x01;
data[1] = 0x00;
data[2] = 0x02;
data[3] = 0x00;
*value_ptr = data;
*value_len = 4;
}
int main(int argc, char *argv[]) {
char *value;
size_t len;
get_value(&value, &len);
printf("length: %zu\n", len);
for (size_t i = 0; i < len; i++) {
printf("0x%02x%c", value[i], (i < len - 1) ? ' ' : '\n');
}
return 0;
}
```
Output:
```
length: 4
0x01 0x00 0x02 0x00
```
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