c - 交换数组中的元素时出现错误输出

Question

The Problem I am trying to solve is:

Consider an array of characters. start scanning each character one by one from both left and right. If both the scanned characters is an alphabet then swap them in the array.

Example:

If the array is ! w , s t u # p a b then I will start scanning from both left and right. ie first I will scan ! and b since both are not alphabets I will not swap. Then I will move to w and a , since both are alphabets I will swap them. I will continue this process till i reach the middle of the array.

我的代码:

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

int main() {

    int p,q,len,i;
    char s[100],temp;

    //ask the length of string
    printf("Enter the number of chars:\n");
    scanf("%d",&len);

    //get each char in the string and store in array s[]
    printf("Enter %d chars:\n",len);
    for(i=0;i<len;i++)
        scanf("%c",&s[i]);

    //start scanning char by char from both sides
    p=0;
    q=len-1;

    while(p<=q)
    {
        // swap chars if both p and q points to a letter
        if(isalpha(s[p]) && isalpha(s[q]))
        {
        temp=s[p];
        s[p]=s[q];
        s[q]=temp;
        }
        //increment p to move towards right
        p++;
        //decrement q to move towards left
        q--;
    }

    //print all chars in the array
    for(i=0;i<len;i++)
        printf("%c",s[i]);

    return 0;
}

我的输入:

10
!w,stu#pab

我的预期输出:

!a,sut#pwb

我得到的输出:

!w,tsu#pa

为什么我得到错误的输出？错误在哪里？

Answer 1

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

int main() {

    int p,q,len,i;
    char s[100],temp;

    //ask the length of string
    printf("Enter the number of chars:\n");
    scanf("%d",&len);

    //get each char in the string and store in array s[]
    printf("Enter %d chars:\n",len);
    scanf("%s",&s[i]);

    //start scanning char by char from both sides
    p=0;
    q=len-1;

    while(p<=q) {
        // swap chars if both p and q points to a letter
        if(isalpha(s[p]) && isalpha(s[q])) {
            temp=s[p];
            s[p]=s[q];
            s[q]=temp;
        }
        //increment p to move towards right
        p++;
        //decrement q to move towards left
        q--;
    }

    //print all chars in the array
    for(i=0;i<len;i++)
        printf("%c",s[i]);
    return 0;
}