This code is wrong. It actually only loops once, and it is impossible to traverse whether all numbers less than a are divisible by a and whether they are 0.

isprime(int a)

{

int I；

for(I = 2； I & lta；; i++)

{

If (a%i==0)

Returns 0;

other

Returns1;

}

}

In the following references

int isprime (int x)

{

for(int I = 2； I< = sqrt (x); I++) //i as long as it is less than the square of X.

If (0 == x%i) // Jump out of the loop directly when x is divided by i and remains 0.

Break;

If (I < = sqrt (x))

Returns 0;

other

Returns1;

}