Segmentation fault using strcat

Question

Here is my code :

char *name, name_log=\"log-\";

------getting \'name\' from user-----

strcat(name_log, name);
char ext[] =         


        

Answer 1

A completely different solution would be this:

const char *prefix = "log-";
const char *suffix = ".log";
// There's a "char *name" somewhere
int size_needed;
char *result;

size_needed = snprintf(NULL, 0, "%s%s%s", prefix, name, suffix);
result = malloc(size_needed + 1);
snprintf(result, size_needed + 1, "%s%s%s", prefix, name, suffix);

// "result" now contains the desired string.

The nice thing about snprintf is that it returns the number of characters it would write if there was enough space. This can be used by measuring upfront how much memory to allocate which makes complicated and error-prone calculations unnecessary.

If you happen to be on a system with asprintf, it's even easier:

char *result = NULL /* in case asprintf fails */;
asprintf(&result, "log-%s.log", name);
// "result" must be released with "free"