How to get the length of an array in C language

In C language, after defining an array, you can use the sizeof command to obtain the length of the array [the number of elements that can be accommodated]. It is not feasible to obtain the length of the array by passing the array name parameter to the subfunction.

In C language, after defining an array, you can use the sizeof command to obtain the length of the array (the number of elements that can be accommodated)

For example:

{
int data[4];
int length;
length=sizeof(data)/sizeof(data[0]);  //数组占内存总空间，除以单个元素占内存空间大小
printf("length of data[4]=%d", length ); //输出length of data[4]=4
}

It is not feasible to obtain the array length by passing the array name parameter to the sub-function. For example:

int getLength(int[] a){
    int length;
    length=sizeof(a)/sizeof(a[0]); //这样是错误的，得到的结果永远是1
    return length;
}

因为，a是函数参数，到了本函数中，a只是一个指针（地址，系统在本函数运行时，是不知道a所表示的地址有多大的数据存储空间，
这里只是告诉函数：一个数据存储空间首地址），所以，sizoef(a)的结果是指针变量a占内存的大小，一般在32位机上是4个字节。
a[0]是int类型，sizeof(a[0])也是4个字节，所以，结果永远是1。

Therefore, to obtain the array length, the effect can only be achieved by using the above method in the code area where the array is defined.

Recommended tutorial: "c Language Tutorial"

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