2018.2.12

（1）大小写转换和putchar(),getchar()函数运用

#include<stdio.h>
int main()
{
     char ch;
     ch = getchar();
     //ch = ch + 'A' - 'a';

     ch = ch-32;

     putchar(ch);
     return 0;
}

（2）域宽、小数位数、左右对齐

#include<stdio.h>
int main()
{
 double data1,data2;
 printf("%9.2f\n",7000.0-6000.0);
 printf("%-9.2f\n",7000.0-6000.0);
 printf("%9.6f\n",7000.0-6000.0);
 printf("%8.2f\n",7000.0-6000.0);
 printf("%6.2f\n",7000.0-6000.0);
 printf("%3.2f\n",7000.0-6000.0);
 return 0;

}
。

（2）switch() 实现简易计算器

#include<stdio.h>

int main()
{
     int data1,data2;
     char op;
     scanf("%d %c%d",&data1,&op,&data2);    //%c前加空格可以忽略一切空白符
     switch(op){
     case'+':
          printf("%d",data1+data2);
          break;                                                    //记得加‘：’ 记得写break;
     case'-':
          printf("%d",data1-data2);
          break;
     case'x':
     case'*':
          printf("%d",data1*data2);
          break;
     case'/':
          if(data1 != 0&&data2 != 0)
           printf("%d",data1/data2);
          else
           printf("ERROR");
          break;
     default:
          printf("...");
 }
 return 0;
}