以下代码摘自linux程序设计 英文名：beginning linux programming
#include <stdio.h>
#include <stdlib.h>
char *menu[] = {
"a - add new record",
"d - delete record",
"q - quit",
NULL,
};
int getchoice(char *greet,char *choices[]);
int main()
{
int choice = 0;
do
{
choice=getchoice("please select an action",menu);
printf("you have chosen: %c\n",choice);
}while(choice != 'q');
exit(0);
}
int getchoice(char *greet,char *choices[])
{
int chosen = 0;
{
int chosen = 0;
int selected;
char **option;
do{
printf("choice: %s\n",greet);
option=choices;
while(*option) //print menu
{
printf("%s\n",*option);
option++;
}
do{
selected = getchar();
}while(selected == '\n');
option = choices;
while(*option)
{
if(selected == *option[0])
{
chosen = 1;
break;
}
break;
}
option++;
}
if(!chosen)
{
printf("incorrect choice,select again\n");
}
}while(!chosen);
return selected;
}
解释：linux is saving the input until the user presses Enter，and then passing
the choice character and the subsequent Enter to the program。
so，each time you enter a menu choice，the program calls getchar，processes the character，
then calls getchar again，which immediately returns with the Enter character。
Linux（like unix）uses a line feed to end lines of text.that is,uses a line feed alone to mean a newline,where
other systems,such as MS-DOS,use a carriage return and a line feed together as a pair.
解释性翻译：linux会暂存用户输入的内容，直到用户按下回车键。假设用户输入a，然后按下回车键。
第一次getchar得到a，第2次getchar得到'\n'，linux用'\n'这一个字符来代替a newline，而MS-DOS用"\r\n"
注意：
以上代码中的
do{
selected = getchar();
}while(selected == '\n');
情景：用户输入a后回车
解读：在读到回车时，由于selected为'\n',故再次执行do语句，即执行第2次getchar，程序会等待用户输入。
巧妙的忽略了'\n'。