我如何使用 strcmp() 检查输入验证方法的字符匹配，使用 int 作为 Obj-C 中的 scanf() 输入？

Question

我正在尝试验证我在用 Obj-C 编写的程序中要求的输入。

这是我的 main() 函数中的代码：

#import <Foundation/Foundation.h>
#import "PointOfSale.h"

int main(int argc, const char * argv[]) {
    @autoreleasepool {

        PointOfSale *myMovieTix = [[PointOfSale alloc] init];
        char l;
        int counter;

        do{
            printf("Welcome to the Regal Entertainment Group Movie     
                    Ticket System.\n \n");
            printf("Please select your language settings from one of 
                    the following options: \n \n");
            printf("\t 1. English \n");
            printf("\t 2. Spanish \n");
            printf("\t 3. Portuguese \n \n");

            printf("Enter your selection here: ");

            scanf("%c", &l);

            if(counter == 6)
            {
                l = 1;
                break;
            }
            else
            {
                counter++;
            }
        } while (![myMovieTix errorCheck: &l]);



    }
    return 0;
}

这是我在 class 中实施的方法，但该程序无法运行：

//this method checks for input errors dont know if will use in main or  
//in implementation file
- (bool) errorCheck: (char *) c
{
    //debug statement
    //printf("inside errorCheck \n");

    //char "array" to use with strcmp()
    char e[1];
    char s[2];
    char p[3];

    //using strcmp() to test input against entry
    if(strcmp(c,e) != 0 || strcmp(c,s) != 0 || strcmp(c,p) != 0)
    {
        //return false if input is anything but a match
        printf("error is returning false because input doesnt match");
        return false;
    }
    else
    {
        //return true if input matches a possible entry
        printf("error is returning true because input matches");
        return true;
    }
}

这是我的输出结果：

Welcome to the Regal Entertainment Group Movie Ticket System.

Please select your language settings from one of the following options: 

     1. English 
     2. Spanish 
     3. Portuguese 

Enter your selection here: 1
error is returning false because input doesnt matchWelcome to the Regal         
Entertainment Group Movie Ticket System.

Please select your language settings from one of the following options: 

     1. English 
     2. Spanish 
     3. Portuguese 

Enter your selection here: error is returning false because input 
doesnt matchWelcome to the Regal Entertainment Group Movie Ticket 
System.

Please select your language settings from one of the following options: 

     1. English 
     2. Spanish 
     3. Portuguese 

Enter your selection here:

无论我输入什么我的 errorCheck() 方法 returns false.

我怀疑发生这种情况是因为我以某种方式没有正确地将输入转换为 char 并且它无法 strcmp() 我试图比较有效性的 char。

有人有什么建议吗？

谢谢！

Answer 1

这是有效的代码。这只是正确声明我的字符的问题：

//this method checks for input errors in the language selection menu
- (bool) errorCheck: (char) c
{
    //debug statement
    //printf("inside errorCheck \n");

    //char "array" to use with strcmp()
    char e = '1';
    char s = '2';
    char p = '3';

    //printf("c deref: %c \n", c);//debug statement

    //printf("comparison: %c = %c \n", c, s);//spanish char debug 
    //statement

    //using strcmp() to test input against entry
    if(c == e || c == s || c == p)
    {
        //return true if input matches a possible entry
        //printf("error is returning true because input matches \n  
        //\n"); //debug statement
        return true;
    }
    else
    {
        //return false if input is anything but a match
        //printf("error is returning false because input doesnt match 
        //\n \n");//debug statement
        return false;
    }
}

我如何使用 strcmp() 检查输入验证方法的字符匹配，使用 int 作为 Obj-C 中的 scanf() 输入？

how do i use strcmp() to check for a char match for an input validation method using an int as input with scanf() in Obj-C?

validation

objective-c

strcmp