toupper函数及一些小程序

 toupper

   原型：extern int toupper(int c);

   用法：#include <ctype.h>

   功能：将字符c转换为大写英文字母

   说明：如果c为小写英文字母，则返回对应的大写字母；否则返回原来的值。

   举例：

       // toupper.c

       #include <syslib.h>
       #include <ctype.h>

       main()
       {
         char *s="Hello, World!";
         int i;

         clrscr();        // clear screen
         printf("%s\n",s);
         for(i=;i<strlen(s);i++)
         {
           putchar(toupper(s[i]));
         }

         getchar();
         return ;
       }

//---------------------------------1
#include <stdio.h>
#include<stdlib.h>
void main()
{
    printf("0 & 0 is %d\n",  & );
    printf("0 & 1 is %d\n",  & );
    printf("1 & 1 is %d\n",  & );
    printf("1 & 2 is %d\n",  & );
    printf("15 & 127 is %d\n",  & );
    system("pause");
}
//------------------------------2
#include <stdio.h>
#include<stdlib.h>
void main()
{
    int value = 0xFF;

    printf("The inverse of %X is %X\n", value, ~value);
    system("pause");
}
//-------------------------------3
#include <stdio.h>
#include<stdlib.h>
void main()
{
    printf("0 | 0 is %d\n",  | );
    printf("0 | 1 is %d\n",  | );
    printf("1 | 1 is %d\n",  | );
    printf("1 | 2 is %d\n",  | );
    printf("128 | 127 is %d\n",  | );
    system("pause");
}
//------------------------------------4
#include <stdio.h>
#include<stdlib.h>
void main()
{
    printf("0 ^ 0 is %d\n",  ^ );
    printf("0 ^ 1 is %d\n",  ^ );
    printf("1 ^ 1 is %d\n",  ^ );
    printf("1 ^ 2 is %d\n",  ^ );
    printf("15 ^ 127 is %d\n",  ^ );
    system("pause");
}
//------------------------------------5
#include <stdio.h>
#include<stdlib.h>
void main()
{
    printf("The letter is %c\n", 'A');
    printf("The letter is %c\n", );
    system("pause");
}
//---------------------------------------6
#include <stdio.h>
#include<stdlib.h>
void main()
{
    char letter;

    int vowel_count = ;
    int consonant_count = ;

    for (letter = 'A'; letter <= 'Z'; letter++)
        switch (letter) {
        case 'A':
        case 'E':
        case 'I':
        case 'O':
        case 'U': vowel_count++;
            break;
        default: consonant_count++;
    };

    printf("The number of vowels is %d\n", vowel_count);
    printf("The number of vowels is %d\n", consonant_count);
    system("pause");
}
//------------------------------------------------------------7
#include <stdio.h>
#include <conio.h>
#include <ctype.h>
#include <stdlib.h>

void main()
{
    char letter;

    do {
        printf("A Display directory listing\n");
        printf("B Display disk information\n");
        printf("C Change system date\n");
        printf("Q Quit\n");
        printf("Choice: ");

        letter = getchar();
        letter = toupper(letter);

        if (letter == 'A')
            system("DIR");
        else if (letter == 'B')
            system("CHKDSK");//不能用
        else if (letter == 'C')
            system("DATE");
    } while (letter != 'Q');
    system("pause");
}