That would introduce a bug. See the following: #include <stdio.h> int main() { printf("%lu\n", strlen("_shutdown")); printf("%lu\n"

That would introduce a bug. See the following: #include <stdio.h> int main() { printf("%lu\n", strlen("_shutdown")); printf("%lu\n", sizeof("_shutdown")); return 0; } This prints the numbers 9 and 10 (on gcc I have). So if you used `sizeof(...)+1` when calculating the length argument for strcmp you'd be comparing the 9-byte string, the null terminator and one character of random nonsense.