如何将字符串和数字组合成一个 scanf 函数

Question

当我向用户询问地址时，每次输入数字时，我的程序都会结束，我意识到每次输入字符时它都会继续运行，但是当我同时输入字符串和数字时，它会自动结束

#include <stdio.h>

int main() 
{
    int createAccount;
    char firstName[10];
    char lastName [10];
    char address[20];
    char city[15];
    int zip;
    int existingUser;
    int customerSupport;
    int pendingStatements;
    char userName[10];
    printf("1. Create Account\n");
    printf("2. Login to existing user\n");
    printf("3. Customer support\n");
    printf("4. Check pending statements \n");
    printf("Enter: ");

    scanf("%d, %d, %d, %d", &createAccount, &existingUser, &customerSupport, &pendingStatements);

    if (createAccount == 1)
    {
        printf("Name: ");
        scanf("%s", firstName);

        printf("Last Name: ");
        scanf("%s", lastName);

        printf("Address:  ");
        scanf("%s", address);

        printf("City: ");
        scanf("%s", city);

        printf("Zip: ");
        scanf("%d", &zip);
    }
    else if (existingUser == 2)
    {
        printf("Username: ");
        scanf("%s", userName);
    }

}

Answer 1

您的第一个 scanf() 正在尝试读取以逗号分隔的 4 个数字。但用户一次只能输入一个菜单选项，而不是 4 个不同的数字。因此，剩余的scanf() 调用均无效。

int choice;
scanf("%d", &choice);
if (choice == 1) {
    ...
} else if (choice == 2) {
    ...
} else if (choice == 3) {
    ...
} else if (choice == 4) {
    ...
} else {
    printf("Invalid choice %d\n", choice);
}

Answer 2

在scanf 中，如果您在输入第一个值时使用多个变量，它将分配给第一个给定变量。在良好的编码scanf 中仅使用一个变量。

前-：

int num1, num2;
printf("Enter numbers = ");
scanf("%d %d", &num1, &num2);

printf("%d\n", num1);
printf("%d\n", num2);

输出

Enter numbers = 1
//It shows blank space it means you have to enter second number
1
2

//You can input two numbers by puting spaces among them. Then it will assign given variables
Enter number = 1 2
1
2

您可以看到第一个输入的值总是分配给第一个变量。因为我们不需要多个变量来完成一项工作。只使用一个变量就可以了

在您的情况下，您必须使用一个变量来检查状态

#include <stdio.h>

int main() 
{

    int choose = 0;
    char firstName[10];
    char lastName [10];
    char address[20];
    char city[15];
    int zip;
    char userName[10];

    printf("1. Create Account\n");
    printf("2. Login to existing user\n");
    printf("3. Customer support\n");
    printf("4. Check pending statements \n");
    printf("Enter: ");

    scanf("%d", &choose);


    if (choose== 1)
    {
        printf("Name: ");
        scanf("%s", firstName);

        printf("Last Name: ");
        scanf("%s", lastName);

        printf("Address:  ");
        scanf("%s", address);

        printf("City: ");
        scanf("%s", city);

        printf("Zip: ");
        scanf("%d", &zip);
    }
    else if (choose== 2)
    {
        printf("Username: ");
        scanf("%s", userName);

    }
    else if (choose== 3)
    {
        printf("..........");
    }
    else if (choose== 4)
    {
        printf("..........");
    }
    else
    {
        printf("Error number\n");
    }

    return 0;

}

Answer 3

#include <stdio.h>

int main() 
{

//int createAccount;
char firstName[10];
char lastName [10];
//int address;
char address[20];
char city[15];
int zip;
char password[10];
int choice;



// int existingUser;
// int customerSupport;
// int pendingStatements;
char userName[10];
printf("1. Create Account\n");
printf("2. Login to existing user\n");
printf("3. Customer support\n");
printf("4. Check pending statements \n");
printf("Enter: ");
scanf("%d", &choice);

if (choice == 1)
{
    printf("Name: ");
    scanf("%s", firstName);

    printf("Last Name: ");
    scanf("%s", lastName);

    printf("Address:  ");
    scanf("%s", address);

    printf("City: ");
    scanf("%s", city);

    printf("Zip: ");
    scanf("%d", &zip);
}
else if (choice == 2)
{
    printf("Username: ");
    scanf("%s", userName);
    printf("Password: ");
    scanf("%s", password);
}


}