Question

我打算为主要车型（瑞典汽车）提供简要描述页面。我还想表明沃尔沃和萨博在下拉列车中属于瑞典汽车。然后当我点击沃尔沃时，它应该导航到沃尔沃描述页面。如何将optgroup标签显示为最初选择的？

谢谢。

#include <stdio.h>
#include <string>
#include <ctype.h>

int main()
{
    int strLength;
    int *ptr_strLength;
    char textStream[];
    int cont = 1;
    while (cont != 0)
    {
        scanf("%s", textStream[]);
        strLength = strlen(textStream[]);
    }
    ptr_strLength = &strLength;
    void findLetters(ptr_strLength);
)

    void findLetters(int *ptr) //find occurences of all letters
    {
        int upLetters[26];
        int loLetters[26];
        char text[];
        int index;
        int a = 65;
        int lowA = 97;
        int b = 0;
        int c = 0;
        int d = 0;
        int e = 0;
        int i = 0;
        int length;
        length = *ptr;

        while (textStream[i] != '\0')
        {
            for (; i < length ); i++)
            {
                if (isalpha(textStream[i])) //checks if char is an alphabet
                {
                    for (; a < 123); a++) 
                    {
                        if (textStream[i] = a)
                        {
                            if (textStream[i] > 64 && textStream[i] < 91) //stores occurrences of uppercase letters
                            {
                                textStream[i] - a = index;
                                upLetters[index] = upLetters[index] + textStream[i] - textStream[i] + 1;
                            }


                            if (textStream[i] > 89 && textStream[i] < 123) //stores occurrences of lowercase letters
                            {
                                textStream[i] - lowA = index;
                                loLetters[index] = loLetters[index] + textStream[i] - textStream[i] + 1;
                            }
                         }
                    }
                }

                printf("Number of Occurrences of letters\n\n");

                if(upLetters[0] > 0)
                {
                    printf("A : \t%d\n", upLetters[0]);
                }
                if(upLetters[1] > 0)
                {
                    printf("B : \t%d\n", upLetters[1]);
                }
                if(upLetters[2] > 0)
                {
                    printf("C : \t%d\n", upLetters[2]);
                }
                if(upLetters[3] > 0)
                {
                    printf("D : \t%d\n", upLetters[3]);
                }
                if(upLetters[4] > 0)
                {
                    printf("E : \t%d\n", upLetters[4]);
                }
                if(upLetters[5] > 0)
                {
                    printf("F : \t%d\n", upLetters[5]);
                }
                if(upLetters[6] > 0)
                {
                    printf("G : \t%d\n", upLetters[6]);
                }
                if(upLetters[7] > 0)
                {
                    printf("H : \t%d\n", upLetters[7]);
                }
                if(upLetters[8] > 0)
                {
                    printf("I : \t%d\n", upLetters[8]);
                }
                if(upLetters[9] > 0)
                {
                    printf("J : \t%d\n", upLetters[9]);
                }
                if(upLetters[10] > 0)
                {
                    printf("K : \t%d\n", upLetters[10]);
                }
                if(upLetters[11] > 0)
                {
                    printf("L : \t%d\n", upLetters[11]);
                }
                if(upLetters[12] > 0)
                {
                    printf("M : \t%d\n", upLetters[12]);
                }
                if(upLetters[13] > 0)
                {
                    printf("N : \t%d\n", upLetters[13]);
                }
                if(upLetters[14] > 0)
                {
                    printf("O : \t%d\n", upLetters[14]);
                }
                if(upLetters[15] > 0)
                {
                    printf("P : \t%d\n", upLetters[15]);
                }
                if(upLetters[16] > 0)
                {
                    printf("Q : \t%d\n", upLetters[16]);
                }
                if(upLetters[17] > 0)
                {
                    printf("R : \t%d\n", upLetters[17]);
                }
                if(upLetters[18] > 0)
                {
                    printf("S : \t%d\n", upLetters[18]);
                }
                if(upLetters[19] > 0)
                {
                    printf("T : \t%d\n", upLetters[19]);
                }
                if(upLetters[20] > 0)
                {
                    printf("U : \t%d\n", upLetters[20]);
                }
                if(upLetters[21] > 0)
                {
                    printf("V : \t%d\n", upLetters[21]);
                }
                if(upLetters[22] > 0)
                {
                    printf("W : \t%d\n", upLetters[22]);
                }
                if(upLetters[23] > 0)
                {
                    printf("X : \t%d\n", upLetters[23]);
                }
                if(upLetters[24] > 0)
                {
                    printf("Y : \t%d\n", upLetters[24]);
                }
                if(upLetters[25] > 0)
                {
                    printf("Z : \t%d\n", upLetters[25]);
                }

                if(loLetters[0] > 0)
                {
                    printf("a : \t%d\n", upLetters[0]);
                }
                if(loLetters[1] > 0)
                {
                    printf("b : \t%d\n", upLetters[1]);
                }
                if(loLetters[2] > 0)
                {
                    printf("c : \t%d\n", upLetters[2]);
                }
                if(loLetters[3] > 0)
                {
                    printf("d : \t%d\n", upLetters[3]);
                }
                if(loLetters[4] > 0)
                {
                    printf("e : \t%d\n", upLetters[4]);
                }
                if(loLetters[5] > 0)
                {
                    printf("f : \t%d\n", upLetters[5]);
                }
                if(loLetters[6] > 0)
                {
                    printf("g : \t%d\n", upLetters[6]);
                }
                if(loLetters[7] > 0)
                {
                    printf("h : \t%d\n", upLetters[7]);
                }
                if(loLetters[8] > 0)
                {
                    printf("i : \t%d\n", upLetters[8]);
                }
                if(loLetters[9] > 0)
                {
                    printf("j : \t%d\n", upLetters[9]);
                }
                if(loLetters[10] > 0)
                {
                    printf("k : \t%d\n", upLetters[10]);
                }
                if(loLetters[11] > 0)
                {
                    printf("l : \t%d\n", upLetters[11]);
                }           
                if(loLetters[12] > 0)
                {
                    printf("m : \t%d\n", upLetters[12]);
                }
                if(loLetters[13] > 0)
                {
                    printf("n : \t%d\n", upLetters[13]);
                }
                if(loLetters[14] > 0)
                {
                    printf("o: \t%d\n", upLetters[14]);
                }
                if(loLetters[15] > 0)
                {
                    printf("p : \t%d\n", upLetters[15]);
                }
                if(loLetters[16] > 0)
                {
                    printf("q : \t%d\n", upLetters[16]);
                }
                if(loLetters[17] > 0)
                {
                    printf("r : \t%d\n", upLetters[17]);
                }
                if(loLetters[18] > 0)
                {
                    printf("s : \t%d\n", upLetters[18]);
                }
                if(loLetters[19] > 0)
                {
                    printf("t : \t%d\n", upLetters[19]);
                }
                if(loLetters[20] > 0)
                {
                    printf("u : \t%d\n", upLetters[20]);
                }
                if(loLetters[21] > 0)
                {
                    printf("v : \t%d\n", upLetters[21]);
                }
                if(loLetters[22] > 0)
                {
                    printf("w : \t%d\n", upLetters[22]);
                }
                if(loLetters[23] > 0)
                {
                    printf("x : \t%d\n", upLetters[23]);
                }
                if(loLetters[24] > 0)
                {
                    printf("y : \t%d\n", upLetters[24]);
                }
                if(loLetters[25] > 0)
                {
                    printf("z : \t%d\n", upLetters[25]);
                }


             }
         }

Answer 1

我相信你要求的东西会像这样呈现：

enter image description here

这不是严格，因为您无法“选择”选项组标签。为了获得你正在寻找的效果，你将不得不执行一些技巧。

我们可以将自定义标签放入span，并将此范围绝对放在select上，以使初始选择显示为作为选项组标签。之后我们需要一些javascript来伪造click和change事件，您可以在下面看到一个工作示例。但是，这就是你的html的样子：

<div class="select-wrapper">
 <span>Swedish Cars</span>
 <select>
  <optgroup class="swe-car" label="Swedish Cars">
   <option value="volvo">Volvo</option>
   <option value="saab">Saab</option>
  </optgroup>
 </select> 
</div>

https://jsfiddle.net/atbqtnq8/

Answer 2

另一个解决方案是让第一个选项与optgroup标签相同，然后在下拉列表聚焦时隐藏它。

ParameterFilter

https://jsfiddle.net/atbqtnq8/13/

Answer 3

这个怎么样？我从另一个问题Selectable <optgroup> in HTML <select> tag复制答案

.optionGroup {
    font-weight: bold;
    font-style: italic;
}
    
.optionChild {
    padding-left: 15px;
}

<select>
    <option value="Swedish Cars" class="optionGroup">Swedish Cars</option>
    <option value="volvo" class="optionChild">volvo</option>
    <option value="saab" class="optionChild">saab</option>
</select>

在下拉列表中选择optgroup标签

3 个答案: