c - C中未声明的标识符

Question

我正在尝试在 visual studio 2012 express 中用 C 语言编译一个小型银行程序。它向我显示了几乎所有变量的错误“未声明的标识符”和这个错误“语法错误:缺少';'在“类型”之前。请告诉我正确的语法。谢谢。

#include<stdio.h>
#include<conio.h>
int main()
{
printf("Welcome to skybank\n");
int deposit,withdraw,kbalance;
char option;
printf("Press 1 to deposit cash\n");
printf("Press 2 to Withdraw Cash\n");
printf("Press 3 to Know Your Balance\n");
scanf_s("%c",option);
int decash,wicash;
switch(option)
{
int balance;
printf("Enter your current Balance\n");
scanf_s("%d",&balance);
case 1:
    printf("Enter the amount you want to deposit\n");
    scanf_s("%d",&decash);
    printf("Thank You\n");
    printf("%d have been deposited in your account\n",decash);
    break;
case 2:
    printf("Enter the amount you want to withdraw\n");
    scanf_s("%d",&wicash);
    int wibal;
    wibal=balance-wicash;
    printf("Thank You\n");
    printf("%d have been withdrawed from your account\n",wicash);
    printf("Your balance is %d\n",wibal);
    break;
case 3:
    printf("Your balance is Rs.%d\n",balance);
    break;
default:
    printf("Invalid Input\n");
    break;
}
getchar();
}

Answer 1

Microsoft C 编译器仅支持 25 年前的语言版本。限制之一是所有变量必须在任何其他语句之前声明。因此，将所有变量声明移至函数顶部。

我看到的下一个错误是将 scanf_s 与 %c 格式字符串一起使用。您必须传递一个指向变量的指针，并传递要读取的字符数。

scanf_s("%c", &option, 1);

同样，您需要传递一个地址来读取balance。

您还需要更改 switch 语句，使其仅包含 case。将裸指令移到外面。

您对选项 的阅读将不起作用。因为当您检查 1 时，您正在检查具有 ASCII 代码 1 的字符。将 option 更改为 int 并使用 读取%d.

也许您正在寻找这样的东西:

#include<stdio.h>
#include<conio.h>

int main(void)
{
    int deposit,withdraw,kbalance;
    int option;
    int decash,wicash;
    int balance;
    int wibal;

    printf("Welcome to skybank\n");
    printf("Press 1 to deposit cash\n");
    printf("Press 2 to Withdraw Cash\n");
    printf("Press 3 to Know Your Balance\n");
    scanf_s("%d", &option);
    printf("Enter your current Balance\n");
    scanf_s("%d", &balance);
    switch(option)
    {
        case 1:
            printf("Enter the amount you want to deposit\n");
            scanf_s("%d", &decash);
            printf("Thank You\n");
            printf("%d have been deposited in your account\n", decash);
            break;
        case 2:
            printf("Enter the amount you want to withdraw\n");
            scanf_s("%d", &wicash);
            wibal=balance-wicash;
            printf("Thank You\n");
            printf("%d have been withdrawed from your account\n", wicash);
            printf("Your balance is %d\n", wibal);
            break;
        case 3:
            printf("Your balance is Rs.%d\n", balance);
            break;
        default:
            printf("Invalid Input\n");
            break;
    }
    getchar();
}