例题6-1：

#include
     
      int main(void){    int i;    char ch_lower,ch_upper;    for(i=1;i<=6;i++)    {        scanf("%c",&ch_lower);        if(ch_lower>='a'&&ch_lower<='z')            ch_upper=ch_lower-'a'+'A';        printf("%c->%c->%d\n",ch_lower,ch_upper,ch_upper%10);    }    return 0;}
     

例题6-2：

#include
     
      int main(void){    char ch = 'w';    int a =2,b=3,c=1,d,x=10;    printf("%d",a>b==c);    printf("%d",d=a>b);    printf("%d",ch>'a'+1);    printf("%d",d=a+b>c);    printf("%d",b-1==a!=c);    printf("%d\n",3<=x<=5);    return 0;}
     

例题6-3：

#include
     
      int main(void){    char ch = 'w';    int a = 2,b = 0,c = 0;    float x=3.0;    printf("%d",a && b);    printf("%d",a||b && c);    printf("%d",!a && b);    printf("%d",a||3+10&&2);    printf("%d",!(x == 2));    printf("%d",!x == 2);    printf("%d\n",ch||b);    return 0;}
     

例题6-5：

#include
     
      int main(void){    char ch;    printf("input characters:");    ch = getchar( );    while(ch!='\n'){        if( ch>='A'&& ch<='Z')            ch = ch -'A'+'a';        else if (ch>='a'&&ch<='z')        ch=ch-'a'+'A';        putchar(ch);        ch=getchar( );    }    return 0;}