a$.$Why do poreder to work with C$++$ string over c$-$string?

b$.$ You need to pass a large vector to a function and the function and the function will not modify it$.$ Why is it better to pass it by reference with const key word than pass it by value?

c$.$ Why is it better to set up statement $1$ instead of statement $2$ in a program?

statement $1$: if $($denominator $!=0$ && numerator $/$ denominator $>=1)$

statement $2$: if $($numerator $/$ denominator $>=1$ && denominator $!=0)$