unit 14

#include<stdio.h>
 #include<string.h>
 #include<stdbool.h>

 enum spectrum {red,orange,yellow,green,blue,violet};
 const char * colors[]={"red","orange","yellow","green","blue","violet"};

 #define LEN 30

 int main(void)
 {
     char choice[LEN];
     enum spectrum color;
     bool color_is_found=false;

     puts("Enter a color (empty line to quit):");
     while(gets(choice)!=NULL&&choice[0]!='\0')
     {
         for(color=red;color<=violet;color++)
         {
             if(strcmp(choice,colors[color])==0)
             {
                 color_is_found=true;
                 break;
             }
         }
         if(color_is_found)
         {
             switch(color)
             {
                 case red:puts("Rose are red.");
                 break;
                 case orange:puts("Poppies are orange.");
                 break;
                 case yellow:puts("Sunflowers are yellow.");
                 break;
                 case green:puts("Grass is green.");
                 break;
                 case blue:puts("Bluebells are blue.");
                 break;
                 case violet:puts("Violets are violet.");
                 break;
             }
         }
         else
             printf("I don't know about the color %s.\n",choice);
         color_is_found=false;
         puts("Next color,please (empty line to quit):");

     }
     puts("Goodbye!");

     return 0;

 }

 

#include <stdio.h>
#include <string.h>
#include <ctype.h>

char showmenu(void);//显示菜单
void eatline(void);//清除多余输入
void show(void(* fp)(char *), char *str);//显示结果
void ToUpper(char *);//转为大写
void ToLower(char *);//转为小写
void Transpose(char *);//大小写相互转化
void Dummy(char *);///

int main(void)
{
    char line[81];//接收输入
    char copy[81];//存储输入的复制
    char choice;//存储用户选择
    void (*pfun)(char *);//声明pfun为 一个 返回为空 接收char *的函数指针

    puts("Enter a string (empty line to quit):");
    while(gets(line)!=NULL&&line[0]!='\0')//获取一个将被转换的字符串 判断结束
    {
        while((choice=showmenu())!='n')//显示菜单 获取选项
        {
            switch(choice)//根据选项 对pfun赋值
            {
                case 'u':pfun=ToUpper;break;
                case 'l':pfun=ToLower;break;
                case 't':pfun=Transpose;break;
                case 'o':pfun=Dummy;break;
            }
            strcpy(copy,line);//复制 输入的字符串
            show(pfun,copy);//显示结果
        }
        puts("Enter a string (empty line to quit):");
    }
    puts("Bye");

    return 0;
}

char showmenu(void)
{
    char ans;
    puts("Enter menu choice :");
    puts("u)uppercase l)lowercase");
    puts("t)transposecase o)originalcase");
    puts("n)next string");
    ans=getchar();//获取选择
    ans=tolower(ans);//将ans 转换为小写字母
    eatline();//清除多余输入
    while(strchr("ulton",ans)==NULL)//匹配输入选项是否正确
    {
        puts("Please enter a u,l,t,o, or n;");
        ans=tolower(getchar());
        eatline();
    }
    return ans;
}

void eatline(void)
{
    while(getchar()!='\n')
        continue;
}

void ToUpper(char *str)
{
    while(*str)
    {
        *str=toupper(*str);
        str++;
    }
}

void ToLower(char *str)
{
    while(*str)
    {
        *str=tolower(*str);
        str++;
    }
}

void Transpose(char * str)
{
    while(*str)
    {
        if(islower(*str))//小写转换为大写
            *str=toupper(*str);
        else//大写转换为小写
            if(isupper(*str))
                *str=tolower(*str);
        str++;
    }
}

void Dummy(char *str)
{

}

void show(void (* fp) (char *),char * str)
{
    (*fp)(str);
    puts(str);
}