The c language calculates all primes in a given range

Program functions:

Enter an integer and print out all primes within that integer.

Example program:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
bool IsPrime(int x)
{
　　bool bResult = false;
　　int i, k;
　　k = (int)sqrt(x);
　　for (i = 2; i <= k; i++)
　　{
　　　　if (x % i == 0)
　　　　{
　　　　　　break; 
　　　　}
　　}
　　if (i > k)
　　{
　　　　bResult = true;
　　}
　　else
　　{
　　　　bResult = false;
　　}
　　return bResult;
}
int main()
{
　　int a = 0;
　　int b = 0;
　　int i = 0;
　　printf(" Please enter the 1 Integers: ");
　　scanf("%d",&a);
　　for (i = 3; i <= a; i++)
　　{
　　　　if (IsPrime(i))
　　　　{
　　　　　　printf("%d\n",i);
　　　　}
　　}
　　system("pause");
　　return 0;
}

Program analysis:

1, IsPrime () function is used to determine whether an integer is prime. If it is, true is returned; otherwise, false is returned. In this function, because the C library function sqrt () is called, #include is included in the header file.

2, the scanf_s () function is used to get the data entered by the user and save this data into a local variable.

Summary:

1, math. h header file declares some common mathematical operations, such as power, square root, etc. If you want to use the C standard library of functions, you need to include the header file for the function.

2. We can use the scanf() function to get data from the terminal.