#include <string.h>
int main() {
const char P = 'P';
// ...
char pstr[2] = { P, 0 };
char buffer[32] = {0};
int num = 1;
int len = sprintf(buffer, "%d", num);
printf("len: %d\n", len);
char* dest = malloc(len + 2);
strcpy(dest, pstr);
strncat(dest, buffer, len);
printf("Result: %s\n", dest);
free(dest);
return 0;
}