Arduino gets the length of the array

hypothesis , Currently, there is such an array

String str[]={
    "ddd","ddd","dsgsd","fdsf","oooo"};

Use sizeof() function

sizeof(str) Is the total byte length of the array ,
sizeof(str[0]) Is to get the byte length of one bit in the array .
Use total byte length / One byte length .
The result is . Length of array .

Sample code

String str[5]={
    "ddd","ddd","dsgsd","fdsf","oooo"};
int num;
void setup() {
    
  Serial.begin(9600);
  num=sizeof(str) /sizeof(str[0]);
  Serial.print(" The length of the array ：");
  Serial.print(num);
}

void loop() {
    
  
}