Question

C语言编程计算1－3＋5－7＋……－99的值

Answer 1

都是c语言，我用c#回答吧。
using System;
using System.Collections.Generic;
using System.Text;

namespace __3_7
{
class Program
{
static void Main(string[] args)
{
int[] x = new int[50];
int sum = 0;
for (int n = 1; n <= 50; n++)
{
x[n - 1] = 2 * n - 1;
if((n-1)%2==0)
{
sum=sum+x[n-1];
}
else
{
sum=sum-x[n-1];
}
}
Console.WriteLine(sum);
}
}
}

Answer 2

#include <stdio.h>

void main()
{
int sum = 0;
int flag = 1;
int i = 0;
for (i = 0; i < 50; i++)
{
sum += flag * (2 * i + 1);
flag = -flag;
}
printf("the result is %d", sum);
}

Answer 3

main()
{
int result=0;
int i;
int n=1;
for(i=1;i<=99;i=i+2)
{
i=i*n;
result+=i;
n=-n;
}
printf("%d",result);
}

Answer 4

#include <stdio.h>
void main(void)
{int i,sum=0,sign=1;
for(i=1;i<100;i+=2)
{sum=sum+i*sign;
sign=-sign;
}
printf("sum=%d\n",sum);
}