What is the Big O time complexity of the worst case scenario for the following code designed to reverse an array of integers?

void reverse$($int arr$[],$ int size$)\{$

int temp $=0$;

for$($int i $=0$; i $<$ size $/2$; i$++)\{$

temp $=$ arr$[$i$]$;

arr$[$i$]=$ arr$[$size $-1-$ i$]$;

arr$[$size $-1-$ i$]=$ temp;

$\}$

$\}$