C sizeof char pointer

Question

Why is size of this char variable equal 1?

int main(){

char s1[] = \"hello\";

fprintf(stderr, \"(*s1) : %i\\n\", sizeof(*s1) )    // prints out 1

}
         


        

Answer 1

sizeof(*s1) means "the size of the element pointed to by s1". Now s1 is an array of chars, and when treated as a pointer (it "decays into" a pointer), dereferencing it results in a value of type char.

And, sizeof(char) is always one. The C standard requires it to be so.

If you want the size of the whole array, use sizeof(s1) instead.