哈哈,代码挺简单的,就不解释啦,有不懂的在下面留言哈,笔主水平有限,不喜勿喷啦.

#include<stdio.h>
#define max(s,f)(s>f?s:f)

maxnum(int a[], int begin,int c) {   //sizeof在子函数中求不出参数传递的数组大小
	int lengch = c - begin;		//注意sizeof在子函数中与主函数中求数组长度的区别
	if (lengch == 1) {
		return a[begin];
	}
	else {
		return max(a[begin], maxnum(a, begin + 1, c)); 
		
	}
}
int main() {
	int a[] = { 1,4,3,10,2 };
	int c = sizeof(a) / sizeof(a[0]);
	maxnum(a, 0, c);
	int m = maxnum(a, 0,c);
	printf("%d\n", m);
	return 0;```