C语言返回从p开始的n位x

returns x with the n bits that begin at position p inverted(i.e, 1 changed into 0and vice versa), leaving the others unchanged. if n is greater than p, then show"falure".
输入:x,n,p
输出:如上所述
例 输入:13
4
2
输出:17

#include <stdio.h>
#include <assert.h>
 
unsigned invert( unsigned x, int p, int n )
{
    unsigned t;
    assert( p >= n );
    t = x >> ( p - n + 1 );
    x >>= ( p - n + 1 );
    x ^= ~( ~0 << n );
    x = ( x << ( p - n + 1 ) ) | t;
    return x;
}
 
int main()
{
    unsigned x = 13;
    int p = 4, n = 2;
    scanf("%u",&x);
    scanf("%d",&p);
    scanf("%d",&n);
    printf( "%u", invert( x, p, n ) );
    return 0;}