Append ' before and after char[] in C

Question

I am trying to append single quotes before and after a char array. Following is the code I am trying:

static const char str[] = "select * from name";
STATICF boolean test(){
   char[] key = "1234";
   strcat(str,(const char *)"\'");
   strcat(str,key);
   strcat(str,(const char *)"\'");
}

It does not work as I get segmentation fault. How can I fix this?

Answer 1

strcat(str,(const char *)"\'");
strcat(str,key);
strcat(str,(const char *)"\'");

str needs to be big enough to hold the whole concatenated result string, plus \0 to terminate the string. This isn´t the case at your example with the declaration of str as:

static const char str[] = "select * from name";

with str to hold only the size of the old string plus \0. Thus, trying to append more characters causes the segmentation fault.

---

Try to declare str with a fixed size, large enough to hold the result string (the old string of select * from name + \' + 1234 + \' + the terminating \0 which shall be 25 characters in total if I´d counted right).

str needs to be non-constant to change the value of str by the way, so omit static const.

Also omit the cast of (const char *); and replace "\'" with "'".

The result is like the following:

char str[25];
strcpy(str,"select * from name");
STATICF boolean test(){
   char key[] = "1234";
   strcat(str,"'");
   strcat(str,key);
   strcat(str,"'");
}