Can I copy a string in an empty string?

Question

Suppose I do like this to copy the string.

char str[] = \"\";
char *str2 = \"abc\";
strcpy(str, str2);
printf(\"%s\", str);  // \"abc\"
printf(\"%d\", strlen(str         


        

Answer 1

This code is definitely causing a stack problem, though with such a small string, you are not seeing the issue. Take, for example, the following:

#include 
#include 
#include 

int main()
{
        char str[] = "";
        char *str2 = "A really, really, really, really, really, really loooooooooooooooonnnnnnnnnnnnnnnnng string.";
        strcpy(str, str2);
        printf("%s\n", str);
        printf("%d\n", strlen(str));
        return 0;
}

A contrived example, yes, but the result of running this is:

A really, really, really, really, really, really loooooooooooooooonnnnnnnnnnnnnnnnng string.
92
Segmentation fault

This is one of the reasons why the strcpy function is discouraged, and usage of copy and concatenate functions that require specifying the sizes of the strings involved are recommended.