要求:最后的结果只能用一个变量来表示，也就是说k=1,k=1,k=2,k=2,……如此取值下去

int main()
{
    int k;
    for(k=1;k<10;k++) printf("%d,%d,",k,k);
    return 0;
}

难倒无数 - -

1,1,2,2,3,3,4,4,5,5,6,6...

这样的么

for( unsigned long i=2;i;i++)
{     printf( "%d," , i/2); }

如泰勒级数般无限扩展……

编程要有有限性

#include<stdio.h>
main()
{   
    unsigned int k=1;
    bool next=printf("k=%d,k=%d,",k,k);
    while(next)
    {   
        k++;
        printf("k=%d,k=%d,",k,k);
    }
}

#include<stdio.h>
main()
{   
    unsigned int k=1;
    bool next=printf("k=%d,k=%d,",k,k);
    while(next)
    {   
        k++;
        printf("k=%d,k=%d,",k,k);
    }
}

#include<stdio.h>
 main()
 {   
    unsigned  int k=1;
     bool next=printf("k=%d,k=%d,",k,k);
     k++;
     while(next&&k>0)
     {   
         printf("k=%d,k=%d,",k,k);
         k++;
     }
 } 稍微修改一下，这样玩的更爽