#include
#include
//#include<math.h>
int main(void)
{
        int num;    FILE*fp;
fp=fopen("9.txt","r");
fscanf(fp,"%d",&num);    cout<< "hex=" << hex << num < #include
#include<math.h>
int main(void)
{
        int binary[100];
        char data[8];
        int i,temp,sum=0,count=0,n=1;;
    bool sign=false;
        
        FILE*fp;
        fp=fopen("9.txt","r");
        while(!feof(fp))
        {
        fscanf(fp,"%c",&data[count]);
        count  ;
        }
    
        for(i=(count-1);i>=0;i--)
        {
        
      switch(data[i])
          {
          case '0': sum=sum 0*n; break;
          case '1': sum=sum 1*n; break;
          case '2': sum=sum 2*n; break;
          case '3': sum=sum 3*n; break;
             case '4': sum=sum 4*n; break;
      case '5': sum=sum 5*n; break;
          case '6': sum=sum 6*n; break;
          case '7': sum=sum 7*n; break;
          case '8': sum=sum 8*n; break;
          case '9': sum=sum 9*n; break;
      case 'A': sum=sum 10*n; break;
          case 'B': sum=sum 11*n; break;
          case 'C': sum=sum 12*n; break;
          case 'D': sum=sum 13*n; break;
          case 'E': sum=sum 14*n; break;
             case 'F': sum=sum 15*n; break;
          }
          if(sum>0)
          n=n*16;
        }            if(data[0]=='-')
        sum=sum*-1;
        printf("轉成10進制:%d\n",sum);            if(sum<0){
    sum=fabs(sum);
        sign=true;
        }
        
        for(i=0;i<16;i  )
        {
                binary[i]=sum%2;
                temp=sum/2;
                sum=temp;
        }
        printf("Outut:\n");
        printf("signed:");            for(i=15;i>=0;i--)
        {
                if(sign==true)
                {
        binary[15]=1; 
                }
                printf("%d",binary[i]);
        }            printf("\n");
        
for(i=0;i<15;i  )
if(binary[i]==1)
break;            if(sign==true)
        {
                for(i=i 1;i<16;i  )
                {
                        if(binary[i]==0)
                                binary[i]=1;
                        else
                                binary[i]=0;
                }
                 binary[15]=1; 
        }
        
printf("2S:");
        for(i=15;i>=0;i--)
        {
                printf("%d",binary[i]);
        }
return(0);
}

引言: 1.做轉換的數字一定要是10進制嗎?(想做16進制轉別的之類的) 2.另外轉成16進制的數值是小寫的，可以不經過其他的處理，直接改成大寫的嗎? [code]

 fscanf(fp,"%d",&num);    cout<< "hex=" << hex << num <num);    假如num是16進制的數:5A    就可以直接轉換5A為10進制的90     
        

引言: 我的意思是

 fscanf(fp,"%d",&num);    cout<< "hex=" << hex << num <num);    假如num是16進制的數:5A    就可以直接轉換5A為10進制的90

fscanf(fp,"%s",&num);
之後
cout<< "dec=" << num <