Detailed explanation and usage of sqrt() function

The sqrt() function is a function we often use. Below I will introduce some of its usage and usage specifications in detail

Required header files

#include<math.h>

Function prototype

double sqrt(double x);

Function:
sqrt() is used to find the square root of a given value

Common usage errors
The open root of output 36

ignores that the return value of the sqrt() function is of double type. Cause an error

The solution is as follows: the

common canonical writing of the sqrt() function.
For example: We need to judge whether a number is prime or not, we only need to judge whether there is a divisible number between the radicals of 2 and n.
Wrong writing:

bool find(int n)
{
    
    
	for(int i=2;i<=sqrt(n);i++)
	{
    
    
		if(n%i==0)
			return false;
	}
	return true;
}

The above writing method is actually not recommended. Although I often write like this.
But in the process of doing a question, a bug occurred just because of this.
I changed to the correct writing method using the following safe writing
method:

bool find(int n)
{
    
    
	int sql=(int)sqrt(1.0*n);//1.0*n的目的是  隐式转换成浮点数，开根号后再强制转换成整型 
	for(int i=2;i<=sql;i++)
	{
    
    
		if(n%i==0)
			return false;
	}
	return true;
}