# include <stdio.h>
# include <stdlib.h>


int sum(int a1, int b2)
{
        int i, temp, total=0;
        
        if(a1<b2){
                temp=b2;
                b2=a1;
                a1=temp;
               
        }
        
        for(i=a1;i<=b2;i++)
                total += i;
               
        return total;
}


int main(void)
{
        printf("the sum from 1 to 100 is %d\n",sum(1,100));
        
        system("PAUSE");
        
        return 0;
}

-----------------------------------------

        temp=b2;
                b2=a1;
                a1=temp;
我不明這個在記憶體的運行?
請問要怎樣解讀?

謝謝各位師兄師姐回答...
不過小弟是問問題不是太好,現在補充一下
好像這個

# include <stdio.h>

int main(void)
{
   
    int i;
    int sum = 0;
   
        for(i=1; i<=5;i++)
            sum = sum + i;
   
    printf("sum = %d",sum);
    return 0;
}
-----------------------------------------------------

當i=1時,1<5,sum=0+1=1; 1+1=2

當i=2時,2<5,sum=1+1=2; 2+1=3

當i=3時,3<5,sum=2+1=3; 3+1=4

當i=4時,4<5,sum=3+1=1; 4+1=5


是不是這樣理解?

[ 本帖最后由 ngokyau 于 2013-9-12 01:04 编辑 ]

這當又怎樣理解?
int sum(int a1, int b2)
{
       int i=1, temp=100, total=0;
        
        if(a1<b2){
                temp=b2;
                b2=a1;
                a1=temp;
               
        }
        
        for(i=a1;i<=b2;i++)
                total += i;
               
        return total;
}

我邏輯要怎樣理解??

不要保留....小弟錯的請指出耶

# include <stdio.h>
# include <stdlib.h>


int sum(int a1, int b2)
{
        int i, temp, total=0;
        
        if(a1<b2){
                temp=b2;
                b2=a1;
                a1=temp;
               
        }
        
        for(i=a1;i<=b2;i++)
                total += i;
               
        return total;
}


這個是自詝函數...下面是引入函數~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

int main(void)
{
        printf("the sum from 1 to 100 is %d\n",sum(1,100));
        
        system("PAUSE");
        
        return 0;
}