I'm doing my first steps with C (pointers, pointer-pointer etc, I love it), so have mercy if this is a dumb question.
This fragment outputs nothing:
char buf[256];
snprintf(buf, sizeof buf, "output: %s%s%s");
puts("test");
And this fragment outputs "test" (as expected):
char buf[256];
snprintf(buf, sizeof buf, "output: %s%s");
puts("test");
=>test
Question: Which role does snprintf play here? Is there any relationship with the puts-statement or why has the puts no effect/output in the first code?
Because snprintf(buf, sizeof buf, "output: %s%s%s"); requires 3 parameters :
snprintf(buf, sizeof buf, "output: %s%s%s", str1, str2, str3);
and snprintf(buf, sizeof buf, "output: %s%s"); requires 2 parameters:
snprintf(buf, sizeof buf, "output: %s%s", str1, str2);
if you don't pass parameters to snprintf function doesn't mean snprintf wont try to access them. So, the result you see is a segmentation fault result caused by snprintf trying to access "str3" parameter that doesn't exist.