1种做法：
#include <stdio.h>
int main (void)
{
    short int a=-30000;
    long int b=-1000000000;
    unsigned short int c=300000;
    unsigned long int d=1000000000;
    char e='a';
    float f=3.4;
    double h=-3.4;
    long double i=34.55;
    printf("a+c=%u\tX\n",a+c);
    printf("b+d=%u\t\tV\n",b+d);   
    printf("a+e=%d\tV\n",a+e);
    printf("e+f=%f\tV\n",e+f);
    printf("f+h=%f\tV\n",f+h);
    printf("i/f=%f\tV\n",i/f);
    printf("e-i=%f\tV\n",e-i);
    return 0;

}
2，种做法
#include <stdio.h>
int main (void)
{
    int a,b,c,d;
    a=-30000,b=-1000000000,c=300000,d=1000000000;
    char e;
    e='a';
    long double f,h,i;
    f=3.4,h=-3.4,i=34.55;
    printf("a+c=%u\tX\n",a+c);
    printf("b+d=%u\t\tV\n",b+d);   
    printf("a+e=%d\tV\n",a+e);
    printf("e+f=%f\tV\n",e+f);
    printf("f+h=%f\tV\n",f+h);
    printf("i/f=%f\tV\n",i/f);
    printf("e-i=%f\tV\n",e-i);
    return 0;

}



第一种为什么printf("a+c=%u\tX\n",a+c);计算结果不对。
第二种：在整型数据里有几个变量（short int a=-30000;
    long int b=-1000000000;
    unsigned short int c=300000;
    unsigned long int d=1000000000;）为甚么不能统一定义为int.(int a,b,c,d;
                                                              a=-30000,b=-1000000000,c=300000,d=1000000000;)
(   float f=3.4;
    double h=-3.4;
    long double i=34.55;)为甚么不能统一定义为long double.(long double f,h,i;
                                                          f=3.4,h=-3.4,i=34.55;)
运行第二代码直接出错。
     求大师给个解答，谢谢！