c++ template 数组长度

template 
int arrLength(T & arr){
	// 实测并不需要额外处理数组长度为0的情况
	int n = sizeof(arr)/sizeof(arr[0]);
	if((typeid('') == typeid(arr[0])) && n && (arr[n-1] == '')){
		// 如为字符串数组返回的是不包括最后''的长度
		--n;
	}
    return n;
}

注1-例子：

char chs1[] = {'a','b','c'};//{97,98,99}
strlen(chs1) == 4;
sizeof(chs1)/sizeof(chs1[0]) == 3;
arrLength(chs1) == 3;

char chs2[] = {'','b','c'};//{0,98,99}
strlen(chs2) == 0;
sizeof(chs2)/sizeof(chs2[0]) == 3;
arrLength(chs1) == 3;

char chs3[] = {'a','','c'};//{97,00,99}
strlen(chs3) == 1;
sizeof(chs3)/sizeof(chs3[0]) == 3;
arrLength(chs1) == 3;

char chs4[] = "0123";
strlen(chs4) == 4;
sizeof(chs4)/sizeof(chs4[0]) == 5;
arrLength(chs1) == 4;

char chs5[] = {97,98,97,0};
strlen(chs4) == 3;
sizeof(chs4)/sizeof(chs4[0]) == 4;
arrLength(chs1) == 3;//此处判断出错！

注2：
char ch[] = "0123143";类似这样里面的’’会连着后面的数字识别成一个字符’12’(8进制);相当于char ch[] = {48,49,50,12,51};，"0123x89123"中的x89同理