C 函数的意外输出

我正在编写一个函数，用于从给定的字符串中查找字符：

Test.c文件如下所示：

#include<stdio.h>

int findIndex(char *array, char search)
{
    int count=0;
    char test;
    int check = 0, repeat;

    if(search == ',')
        repeat = rand()%10;

    else
        repeat = rand()%11;

    while((test = array[count]) != NULL)
    {
        if(test == search)
        {

            if(check == repeat)
                return count;

          check++;
        }

        count++;
    }

}

int main()
{
    char sc[] = "cn:Y,x509UniqueIdentifier:Y,pseudonym:Y,name:Y,l:Y,street:Y,state:Y,postalAddress:Y,postalCode:Y,telephoneNumber:Y,emailAddress:Y";
    char testchar;  

    printf("Enter the search character: ");
    testchar = getc(stdin);

    printf("The search char found at: %d position.\n",findIndex(sc,testchar));

    fflush(stdin);

    while(testchar != 'N')
    {
        printf("The search char found at: %d posotion.\n",findIndex(sc,testchar));
        printf("Enter the search character: ");
        scanf("%c",&testchar);
                fflush(stdin);
    }        

    return 0;
}

我哪里出错了？

---

请告诉我问题所在以及解决方法。

您可能希望主功能如下所示：

int main()
{
    char sc[] = "cn:Y,x509UniqueIdentifier:Y,pseudonym:Y,name:Y,l:Y,street:Y,state:Y,postalAddress:Y,postalCode:Y,telephoneNumber:Y,emailAddress:Y";
    char testchar;

    printf("Enter the search character: ");
    scanf("%c",&testchar);
    while(testchar != '\n' && getchar() != '\n'); # discard any next chars

    while(testchar != 'N') {
        printf("The search char found at: %d position.\n",findIndex(sc,testchar));
        printf("Enter the search character: ");
        scanf("%c",&testchar);
        while(testchar != '\n' && getchar() != '\n'); # discard any next chars
    }
    return 0;
}

上面的示例生成以下结果：

$ > ./a.out
Enter the search character: Y
The search char found at: 66 position.
Enter the search character: .
The search char found at: 0 position.
Enter the search character: ,
The search char found at: 83 position.
Enter the search character: g
The search char found at: 0 position.
Enter the search character: N
$ >

---

PS:fflush（）不是由ISO为输入流定义的。它在Microsoft的C运行时库中定义，但不可移植。

您的代码中有一条警告，必须更正

while((test = array[count]) != NULL)

上面的行生成警告：指针和整数之间的比较

while((test = array[count])!='\0')

在您的输出中，您将获得两次字符索引，因为换行字符也会被获取，并且它的位置也会被打印出来（当您按下enter键时）

为了避免这种情况，你可以这样做

while(testchar != 'N')
{
       if(testchar!='\n'){//checking whether character is newline
        printf("The search char %d found at: %d posotion.\n",testchar,findIndex(sc,testchar));
        printf("Enter the search character: ");
        scanf("%c",&testchar);

        }
        else
        {
             scanf("%c",&testchar);//reading the newline character but not performing any operation(printing the index )
        }

}        

就是这样，你的程序现在可以运行了

注意：使用fflush（stdin）被认为是一种不好的做法，并且具有未定义的行为。最好不要使用它来刷新输入流，因为它不可移植。请参阅此详细信息

输出

Enter the search character: Y
The search char found at: 66 position.
The search char 89 found at: 128 position.
Enter the search character: J
The search char 74 found at: 0 position.
Enter the search character: o
The search char 111 found at: 85 position.
Enter the search character: N

---

希望有帮助。祝你编码愉快

您是否尝试过在编译时启用警告（例如，-Wall）？我怀疑您会看到一个关于函数返回值的警告。您还会看到一个关于将

char

与指针进行比较的警告，特别是“不同级别的间接寻址”。我调试了您的源代码。它还使用换行符（当您按enter键时）所以它印刷了两次。谢谢大家的评论和建议。

Enter the search character: Y
The search char found at: 66 position.
The search char 89 found at: 128 position.
Enter the search character: J
The search char 74 found at: 0 position.
Enter the search character: o
The search char 111 found at: 85 position.
Enter the search character: N