我可能会提供足够的但很长的故事，我正在研究ATM机程序，我正在尝试将＃34;切换＆＃34;在循环中的main函数中的语句，这样用户可以获得更多的事务。
我遇到一个问题，我会存入100但是当我检查余额时它仍然是0.我知道其他一切正常但是这个循环正在杀了我，我将不胜感激任何帮助！ 不要介意它所在的所有额外的东西，以便了解我正在做的工作
int main ()
{
char option;
float balance ;
int count = 1;
option = displayMenu();
do
{
switch (option)
{
case 'D':
getDeposit(balance);
main();
count++;
break;
case 'W':
getWithdrawal(balance);
main();
count++;
break;
case 'B':
displayBalance(balance);
main();
count++;
break;
case 'Q':
printf("Thank you!");
break;
main();
}
} while ( count <= 5);
return 0;
}
char displayMenu()
{
char option;
printf("\n Welcome to HFC Federal Credit Union \n");
printf("\n Please select from the following menu: \n ");
printf("\n D: Make a deposit \n ");
printf("\n W: Make a withdrawal \n ");
printf("\n B: Check your account balance \n ");
printf("\n Q: To quit \n ");
scanf("\n%c" , &option);
return option;
}
float getDeposit(float balance)
{
float deposit;
printf("\n Please enter the amount you want to deposit! ");
scanf("%f" , &deposit);
balance += deposit;
return balance;
}
float getWithdrawal(float balance)
{
float withdrawal;
printf("\n Please enter the amount you want to withdraw! ");
scanf("%f" , &withdrawal);
balance -= withdrawal;
return balance;
}
void displayBalance(float balance)
{
printf("\n Your current balance is %f " , balance);
}
答案 0 :(得分：4)
你在循环的每次迭代中递归调用main()。只需删除此电话，您就应该好了。
您还需要将函数的返回值分配给balance，否则它们将无法影响其值。
答案 1 :(得分：3)
这段代码有很多问题......这是我的主要指针（但不是全部，我只是回答这个问题）：
你一遍又一遍地调用main，为简单起见，你可以将其视为每次重启应用程序（除了堆栈问题，我忽略了其他令人讨厌的副作用）。
您没有初始化balance（和朋友）变量。它们可能包含“垃圾”数据。
您忽略了您使用的函数的返回值。如果您没有使用指针，则应使用赋值。
您的菜单打印功能已经失控...我怀疑这是否是您想要的。
这是一个快速的脏修复（未经测试）：
int main() {
char option;
float balance = 0;
int count = 1;
do {
option = displayMenu(); // moved into the loop.
switch (option) {
case 'D':
balance = getDeposit(balance);
count++;
break;
case 'W':
balance = getWithdrawal(balance);
count++;
break;
case 'B':
balance = displayBalance(balance);
count++;
break;
case 'Q':
printf("Thank you!");
break;
}
} while (count <= 5);
return 0;
}
char displayMenu(void) {
char option;
printf("\n Welcome to HFC Federal Credit Union \n");
printf("\n Please select from the following menu: \n ");
printf("\n D: Make a deposit \n ");
printf("\n W: Make a withdrawal \n ");
printf("\n B: Check your account balance \n ");
printf("\n Q: To quit \n ");
scanf("\n%c", &option);
return option;
}
float getDeposit(float balance) {
float deposit;
printf("\n Please enter the amount you want to deposit! ");
scanf("%f", &deposit);
balance += deposit;
return balance;
}
float getWithdrawal(float balance) {
float withdrawal;
printf("\n Please enter the amount you want to withdraw! ");
scanf("%f", &withdrawal);
balance -= withdrawal;
return balance;
}
void displayBalance(float balance) {
printf("\n Your current balance is %f ", balance);
}
祝你好运！
答案 2 :(得分：0)
你没有改变main（）中的变量。 你可以改变循环：
do
{
switch (option)
{
case 'D':
balance = getDeposit(balance);
count++;
break;
case 'W':
balance = getWithdrawal(balance);
count++;
break;
case 'B':
displayBalance(balance);
count++;
break;
case 'Q':
printf("Thank you!");
break;
}
} while (count <= 5);
答案 3 :(得分：0)
我认为主要问题是在循环外更新开关控制变量
回应＆＃34; Q＆＃34;结束有点必要......然后只允许5变得不必要
我也修了几件其他东西;并提供了对它们的评论
并且我稍微改进了可测试性（5-> 6）。我保持计数，只是扩展到6，以便进行完整的测试＆＃34; D 100，B，W 50，B，Q＆＃34;。
顺便说一句漂亮的设计，从函数返回平衡，而不是使用指针或全局变量。但是你需要使用返回值而不是忽略它。
/* include necessary headers, do not skip this when making your MCVE */
#include <stdio.h>
/* prototypes of your functions,
necessary to avoid the "immplicitly declared" warnigns
when compiling "gcc -Wall -Wextra"; which you should
*/
char displayMenu(void);
float getDeposit(float balance);
float getWithdrawal(float balance);
void displayBalance(float balance);
/* slightly better header of main, with "void" */
int main (void)
{
char option;
float balance=0.0; /* initialise your main variable */
int count = 1;
/* your very important update of the switch control variable has been moved ... */
do
{
option = displayMenu(); /* ...here */
/* If you do not update your switch variable inside the loop,
then it will forever think about the very first command,
this explains most of your problem.
*/
switch (option)
{
case 'D':
balance=getDeposit(balance); /* update balance */
/* removed the recursive call to main(),
it is not needed as a solution to the problem that the program
always uses the first command (when updating inside the loop)
and otherwise just makes everything much more complicated and
risky.
*/
count++;
break;
case 'W':
balance=getWithdrawal(balance); /* update balance */
count++;
break;
case 'B':
displayBalance(balance);
count++;
break;
case 'Q':
printf("Thank you!");
/* adding a way to get out of the loop,
using a magic value for the count,
this is a mehtod frowned upon by most,
but it minimises the changes needed to your
own coding attempt.
*/
count=0;
break;
}
} while ( (count <= 6)&&(count>0) ); /* additionally check for the magic "Q" value
check against count<=6, to allow testing D,B,W,B,Q */
return 0;
}
/* use explicitly empty parameter list for functions */
char displayMenu(void)
{
char option;
printf("\n Welcome to HFC Federal Credit Union \n");
printf("\n Please select from the following menu: \n ");
printf("\n D: Make a deposit \n ");
printf("\n W: Make a withdrawal \n ");
printf("\n B: Check your account balance \n ");
printf("\n Q: To quit \n ");
scanf("\n%c" , &option);
return option;
}
float getDeposit(float balance)
{
float deposit;
printf("\n Please enter the amount you want to deposit! ");
scanf("%f" , &deposit);
balance += deposit;
return balance;
}
float getWithdrawal(float balance)
{
float withdrawal;
printf("\n Please enter the amount you want to withdraw! ");
scanf("%f" , &withdrawal);
balance -= withdrawal;
return balance;
}
void displayBalance(float balance)
{
printf("\n Your current balance is %f " , balance);
}