C language study notes while statement

Introducing an example: pai approximation to calculate Pi. Given formula, calculated up to the previous 100.

With a for statement:

#include <stdio.h>
#include <math.h>
int main ()
{
	double sum =0,pi,c;
	int n;
	for (n=1;n<=100;n++)	
	{
		c = pow(-1,n+1)/(2*n-1);
		sum = sum + c ;
	}
	pi = 4 * sum;
	printf("pi=%lf\n",pi);
}

With whlie statement:

#include <stdio.h>
#include <math.h>
int main ()
{
	double sum = 0,pi,c=1,s=1;
	int n =1 ; 
	while(fabs(c)>=1e-6)	
	{
		sum = sum + c ;
		s=-s;
		n++;
		c = s/(2*n-1);
	}
	pi = 4 * sum;
	printf("pi=%lf\n",pi);
} 

while statement - "When type"

whlie (条件表达式)
	循环体

Do not ignore their own codes knock this one step will really find a lot of problems

Look at this code, using the while statement 1 + ... 100;

#include <stdio.h>
int main ()
{
	int sum =0,i=1;
	while(i<=100)
	{
		sum = sum + i;
		i=i+1;
	}
	printf("sum=%d\n",sum);
}

while statements and for statements expressed cycle, cycle times are generally suitable for use statement for an uncertain number of cycles with whlie statement.

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