在另一个功能中调用菜单功能
我试图在主要功能中调用菜单功能并让它提示直到用户决定退出，但似乎它没有给我回复.. 我是这个网站编码的新手，让我知道是否有任何例如。发布格式我可以改进！
clearkeyboard功能：
void clearKeyboard(void)
{
int c;
while ((c = getchar()) != '\n' && c != EOF);
}
调用菜单的功能：
void ContactManagerSystem(void)
{
int contactchoice;
int done = 1;
char yesno, c;
do {
clearKeyboard();
contactchoice = menu();
switch (contactchoice) {
case 1:
printf("<<< Feature 1 is unavailable >>>\n");
break;
case 2:
printf("<<< Feature 2 is unavailable >>>\n");
break;
case 3:
printf("<<< Feature 3 is unavailable >>>\n");
break;
case 4:
printf("<<< Feature 4 is unavailable >>>\n");
break;
case 5:
printf("<<< Feature 5 is unavailable >>>\n");
break;
case 6:
printf("<<< Feature 6 is unavailable >>>\n");
break;
case 0:
printf("Exit the program? (Y)es/(N)o: ");
scanf("%c%c", &yesno, &c);
if (yesno == 'Y' || yesno == 'y' && c == '\n') {
done = 0;
break;
}
else if (yesno == 'N' || yesno == 'n')
break;
default:
break;
}
} while (done == 1);
}
菜单功能：
int menu(void)
{
int done = 1;
int choice;
char c;
do {
printf("Contact Management System\n");
printf("-------------------------\n");
printf("1. Display contacts\n");
printf("2. Add a contact\n");
printf("3. Update a contact\n");
printf("4. Delete a contact\n");
printf("5. Search contacts by cell phone number\n");
printf("6. Sort contacts by cell phone numbe\n");
printf("0. Exit\n\n");
printf("Select an option:> ");
int rtn = scanf("%d%c", &choice, &c);
if (rtn == EOF || rtn == 0 || c != '\n')
clearKeyboard();
else if (choice >= 0 && choice <= 6 && c == '\n')
done = 0;
else {
clearKeyboard();
printf("*** OUT OF RANGE *** <Enter a number between 0 and 6>: ");
scanf("%d", &choice);
}
} while (done == 1);
return choice;
}
下面附图是出错的地方，正确的版本应该做案例1，而不是再次保留提示菜单。
不正确的部分
提前致谢!!!
3 个答案:
答案 0 :(得分：1)
您的代码中存在两个问题。
-
menu（）函数返回
int，并且您在int切换案例char中匹配case '1':它应该是case 1: -
替换以下行
带有
scanf("%c%c", &yesno,&c); 的 scanf("%c%c", &c,&yesno);
希望这对你有所帮助。
答案 1 :(得分：1)
有两个问题需要改进。
1）由于menu()返回整数，因此switch case应该有整数而不是字符。
2）
printf("Exit the program? (Y)es/(N)o: ");
scanf("%c%c", &yesno, &c);
您不使用c;
scanf(" %c", &yesno);
就够了。
#include <stdio.h>
void clearKeyboard(void)
{
int c;
while ((c = getchar()) != '\n' && c != EOF);
}
void ContactManagerSystem(void)
{
int contactchoice;
int done = 1;
char yesno, c;
do {
contactchoice = menu();
switch (contactchoice) {
case 1:
printf("<<< Feature 1 is unavailable >>>\n");
break;
case 2:
printf("<<< Feature 2 is unavailable >>>\n");
break;
case 3:
printf("<<< Feature 3 is unavailable >>>\n");
break;
case 4:
printf("<<< Feature 4 is unavailable >>>\n");
break;
case 5:
printf("<<< Feature 5 is unavailable >>>\n");
break;
case 6:
printf("<<< Feature 6 is unavailable >>>\n");
case 0:
printf("Exit the program? (Y)es/(N)o: ");
scanf(" %c", &yesno);
if (yesno == 'Y' || yesno == 'y') {
done = 0;
break;
}
else if (yesno == 'N' || yesno == 'n')
break;
default:
break;
}
} while (done == 1);
}
int menu(void)
{
int done = 1;
int choice;
do {
printf("Contact Management System\n");
printf("-------------------------\n");
printf("1. Display contacts\n");
printf("2. Add a contact\n");
printf("3. Update a contact\n");
printf("4. Delete a contact\n");
printf("5. Search contacts by cell phone number\n");
printf("6. Sort contacts by cell phone numbe\n");
printf("0. Exit\n\n");
printf("Select an option:> ");
scanf("%d", &choice);
if (choice >= 0 && choice <= 6)
done = 0;
else {
clearKeyboard();
printf("*** OUT OF RANGE *** <Enter a number between 0 and 6>: ");
scanf("%d", &choice);
}
} while (done == 1);
return choice;
}
int main(void)
{
ContactManagerSystem();
return 0;
}
输出：
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone numbe
0. Exit
Select an option:> 1
<<< Feature 1 is unavailable >>>
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone numbe
0. Exit
Select an option:> 0
Exit the program? (Y)es/(N)o: Y
答案 2 :(得分：1)
只需进行一些额外的清理工作。您需要通过使用 Ctrl + d （或在windoze上 Ctrl + z ）生成手动EOF来确定如何处理用户取消输入。由于您返回了int值，因此您可以轻松返回-1 EOF案例。
此外，您需要拨打多少次printf来电？一个就足够了，例如
int menu (void)
{
int rtn, choice; /* scanf return, menu choice */
for (;;) { /* loop until valid input or EOF displaying menu */
printf ("\nContact Management System\n"
"-------------------------\n"
" 1. Display contacts\n"
" 2. Add a contact\n"
" 3. Update a contact\n"
" 4. Delete a contact\n"
" 5. Search contacts by cell phone number\n"
" 6. Sort contacts by cell phone number\n"
" 0. Exit\n\n"
"Select an option:> ");
rtn = scanf ("%d", &choice); /* save scanf return */
if (rtn == 1 && 0 <= choice && choice <= 6) /* good value, break */
break;
else if (rtn == EOF) { /* user canceled input, return -1 */
fprintf (stderr, "(user canceled input).\n");
return -1;
}
empty_stdin(); /* empty_stdin for rtn = 0 case */
fprintf (stderr, " error: invalid input.\n");
}
empty_stdin(); /* empty_stdin after good value */
return choice; /* return choice to user */
}
C switch函数提供 case-fallthrough ，直到遇到break语句。您可以在CMS函数中使用此功能，直到填写所有case:语句为止。您可以继续使用fallthrough来处理0 - exit并处理来自EOF的{{1}}（用户取消的输入）返回，例如
menu()完全可以，你可以创建一个相当强大的小菜单系统，例如
void cms (void)
{
for (;;) { /* loop continually calling menu */
int choice = menu();
char c;
switch (choice) {
case 1:
case 2:
case 3: /* use case-fallthrough until setup */
case 4:
case 5:
case 6:
printf("<<< Feature %d is unavailable >>>\n", choice);
break;
case 0:
printf ("exit program [y/n]: "); /* confirm exit */
if (scanf (" %c", &c) == EOF) { /* handle EOF */
fprintf (stderr, "(user canceled input).\n");
return;
}
empty_stdin();
if (c == 'N' || c == 'n') { /* handle no exit */
continue;
break;
}
case -1: /* fallthrough yes exit or EOF in menu */
return;
break;
}
}
}
示例使用/输出
通过 Ctrl + d （或menu()或exit program [y/n]:提示中取消输入的情况>在windoze上按Ctrl + z ：
EOF一切都好，现在检查一个正常的用例，回答No退出，然后是：
$ ./bin/scanf_menu_cms
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> (user canceled input).
$ ./bin/scanf_menu_cms
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> 0
exit program [y/n]: (user canceled input).
最后一个无效的输入案例：
$ ./bin/scanf_menu_cms
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> 4
<<< Feature 4 is unavailable >>>
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> 0
exit program [y/n]: n
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> 0
exit program [y/n]: y
虽然不是错误，但C的标准编码样式避免使用$ ./bin/scanf_menu_cms
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> My dog has fleas!
error: invalid input.
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> -1
error: invalid input.
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> 7
error: invalid input.
Contact Management System
-------------------------
1. Display contacts
2. Add a contact
3. Update a contact
4. Delete a contact
5. Search contacts by cell phone number
6. Sort contacts by cell phone number
0. Exit
Select an option:> 4
<<< Feature 4 is unavailable >>>
或camelCase变量名来支持所有小写，同时保留用于宏和常量的大写名称。这是一个风格问题 - 所以它完全取决于你，但如果不遵循它可能会在某些圈子中产生错误的第一印象。
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