> 我少考虑情况了，但是我将另一种情况加进来后仍然不对。
> #include"string.h"
> #include"stdio.h"
> #include"math.h"
> #define cw 4.19
> #define ci 2.09
> #define temp 335
> 
> void main()
> { double mw,mi,tw,ti;
>   
>   scanf("%lf%lf%lf%lf",&mw,&mi,&tw,&ti);
>  while(mw||mi||tw||ti)
>  {
>     if((mw*cw*tw)>((-mi*ci*ti)+temp*mi))
>          printf("0.0 g of ice and %.1lf g of water at %.1lf C\n",(mw+mi),
>                            ((mw*cw*tw+mi*ci*ti-temp*mi)/(mw*cw+mi*cw)));
>   else if((-mi*ci*ti)<(mw*cw*tw+mw*temp))
>              { if(ti==0&&tw==0)
>                 printf("%.1lf g of ice and %.1lf g of water at 0.0 C\n",mi,mw);
>               if(mw*cw*tw>(-mi*ci*ti))  
>                 printf("%.1lf g of ice and %.1lf g of water at 0.0 C\n",(mi-(mw*cw*tw+mi*ci*ti)/335),(mw+(mw*cw*tw+mi*ci*ti)/335));
>                 else  printf("%.1lf g of ice and %.1lf g of water at 0.0 C\n",(mi+(-mw*cw*tw-mi*ci*ti)/335),(mw-(-mw*cw*tw-mi*ci*ti)/335));
>                 }  
>        else printf("%.1lf g of ice and 0.0 g of water at %.1lf C\n",(mw+mi),
>                            ((mw*cw*tw+mw*temp+mi*ci*ti)/(mi*ci+mw*ci)));
>    scanf("%lf%lf%lf%lf",&mw,&mi,&tw,&ti);
> 
>  }
> }